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=An Observation on the Development of the Mammalian Vomer=
By
Robert J. Terry. From the Department of Comparative Anatomy, Harvard Medical School,
With Two Fiqures.
The name "vomer," given to the unpaired plowshare-shaped bone of the human cranium, has been applied in the works on comparative anatomy to a pair of bones in the skulls of the Sauropsida and Ichthyopsida. This homology, maintained by the earlier writers and by most osteologists up to the present time, is founded largely on the relations of parts in the adult skull. The unpaired vomer of the mammals was explained by assuming it to be the equivalent of a pair fused together, a theory supported by observations on the origin and development of the single vomer in certain teleosts and birds and in man. According to Gaupp^ true paired Anlagen of the vomer have not, however, been seen in the lower mammals.
In 1884 Sutton^ proposed a new homology for the mammalian vomer by claiming its presence in the lower- animals in the parasphenoid, an unpaired bone in the base of the cranium which exists in all classes from the fishes on, except the mammals. The parts in the mammalian cranium which, according to the theory, should correspond with the ichthyopsidan paired vomers, were found in the palatine processes of the premaxillaries. These processes have been observed by Albrecht, Sutton and others to arise independently of, and subsequently to fuse with, the tooth-bearing portions of the prejnaxillaries.
^Gaupp, E. Die Entwickelung des Kopfskelettes. Hertwig's Handbuch der Entwickelungslehre der Wirbeltiere. 1906, Bd. Ill, Zweiter Teil, p. 850.
•Sutton, J. B. Observations on the Parasphenoid, the Vomer and the Palato-pterygoid Arcade. Proc. Zool. Soc, 1884, p. 566.
In later years, Broom^ has contributed much to our knowledge of the comparative anatomy of the vomer, and with evidence adduced from the investigations of Turner, W. K. Parker, Wilson and Symington, he strongly supports the homology of the mammalian vomer and parasphenoid. As to the comparison of the paired vomers of the lower forms w4th the palatine processes of the premaxillaries, he does not agree entirely w^ith Sutton. Broom has suggested the term '^prevomer'^ for the category of bones represented by the paired vomers (of other authors) in the lizard, and finds its homologues in the paired vomers of the Ichthyopsida. But in the great majority of the higher mammals the prevomer does not exist, its place being taken by invasion of the palatine processes of the premaxillaries. These are regarded as true portions of the premaxillaries and not independent elements w^hich Sutton considered them to be. In the dumbbell-shaped bone of Ornithorhynchus and in a median ossification in the nasal region of Miniopterus, Broom identifies the prevomer. These bones, although azygos in the adult, are both derived from a fusion of a pair of splints underlying the cartilages of the vomeronasal organs.
An objection to the comparison of the mammalian vomer and the non-mammalian parasphenoid lies in the fact that the latter presents in the series of animals a history of retrogression ; in the lowest forms the parasphenoid reaches forward to the ethmoidal region, w^hereas in most reptile? and birds its anterior end is far back and away from this region. A more serious obstacle to the new homology is the circumstance, already mentioned, of the single vomer developing from a pair of centers. The one instance in mammals might wvll be taken to be an exception to the rule of single origin, if single origin were known to be the rule. But how many studies have been made by modem methods to determine this matter ?
"Broom, R. On the Iloinology of the Palatine Process of the Mammalian PremaxUlary. Proc. Linn. Soe. N. S. W., 1895. Vol. X, p. 477-485.
On the Occurrence of an Apparently Distlnet I'revomer In Gomphognathus. Jour. Anat. and Physiol., 1896, Vol. XXXI.
On the Mammalian and Reptilian Vomerine Bones. Proc. Linn. Soe. N. S. W., 1902, Vol. XXVII, part 4, p. 545-,')G0.
During the reconstruction of the cranium of a cat embryo there was observed a tendency to bilateral formation of the vomer, and my attention was thereby directed to the question of the origin of this bone in the mammals. A review of the series in the Harvard Embryological Collection resulted in finding one instance of paired origin of the vomer, and tliat in a marsupial. The discovery by Fuchs* of the remains of the parasphenoid in a Didclphys embryo and its bearing on the homology of the mammalian vomer, induced me at this time to communicate the observation. Through the courtesy of Professor ilinot I have been enabled recently to review the sections of the heads of three pouch-specimens of Caluromys (Didelphys) philander in which the paired origin of the vomer had been noted.
Figs. 1 and 2. — Transverse sections tbroiigh the nasal region of a 17 mm. specimen of Caluromys philander; 1, through the anterior ends of the vomers ; 2, through the middle of the vomers. Harvard Emb. Coll., Series 707, Sections 245 and 228. X 39 diam.
A, cartilaginous nasal septum; B, palate; C, vomer; Z>, palate process of premaxilla ; £7, vomeronasal organ of Jacobson.
Fuchs, Hugo. Ueber einen Rest des Parasphenoids bei einem rezenten Saugetiere. Anat. Anz., 1908, Bd. 32, p. 584-590.
In a specimen 18 mm. in length there is present a pair of vomers. These elongate ossifications lie approximately parallel with the ventral edge of the cartilaginous nasal septum and extend from its caudal end forward as far as the middle of the vomero-nasal cartilages of Jacobson. Here the septum is continuous ventrally with the palate, and in this region the vomers are connected with one another across the median line. The connection is a feeble one, consisting of a few delicate bony trabeculse which are present in only three of the section.^. Beyond this place in the caudal direction, the septum and palate are separated by a space, so that the nasal cavities are in communication with each other from side to side. In this region the two vomers are seen to diverge as they are followed backward. Each bone for the most part is compressed, with sharp edges and surfaces directed more or less obliquely — ventrally toward its anterior end, ventrolaterally in the middle of its extent. Anterior to the vomers lie the paired palatine processes of the premaxillaries, adapted to the convex surfaces of the vomero-nasal cartilages. A parasphenoid ossification center was not observed.
The conditions here described were found to be essentially the same in the two other specimens examined which were from the same pouch.
The study of younger specimens may decide whether or not the bony bridges are secondary connections between a pair of independent vomerine ossifications. The large size and advanced state of ossification of the lateral parts is indicative of an earlier origin for them than for the insignificant median ossification. The osteogenetic tissue in which the vomers are developing is disposed in two lateral masses of niesenchyma, connected here and there by strands of the same tissue stretching across the middle line ventrad of the nasal septum. In sections passing through its anterior end, the vomerine ossification tract is found to be unpaired and to be situated beneath the nasal septum, from the perichondrium of which it is well separated. This median mass of osteogenetic tissue is, however, of small extent in comparison with the lateral masses of the tissue, and, except anteriorly, presents itself in strands and not as a continuous bed of mesenchyma.
Relics of the pair of plates which fuse to form the vomer in man are to be found in the ake, projecting conspicuously at the caudal end of the bone. This suggests the probability of the alse of the cat's vomer and of the vomers of other mammals having an origin from paired parts of the developing bone. The dumbbell-shaped bone of Ornitliorhynchus is bifid caudally, a condition which seems to follow from the original paired state of this element. It is not, however, my intention at this time to enter into the question of the phylogeny of the vomer. The object of this communication is to record the paired origin of the vomer in a low mammal, in which class generally it must be insisted that further study of the development is necessary before the bone can be regarded as azygos in its beginning.
Received for publication August 9, 1909.
==D ALMOST COMPLETE SUPPRESSION OF THE CUNEIFORM BONES OF A FOOT. AN INSTANCE OF VITAL READJUSTMENT==
BY
THOMAS DWIGHT. Parkman Professor of Anatomy, Harvard Medical School.
With Two Figubes.
The following observation is reported not only because it is perhaps unique, but because it is a very striking instance of what might be called vital readjustment
The foot is that of a white man aged 78, and apparently had not attracted any particular notice either before or during dissection. By an unfortunate mischance, the other foot has been lost sight of. The hands showed nothing remarkable beyond disease of one joint of a thumb. The foot consists — apart from the phalanges, which are free and apparently healthy — of the following pieces : the astragalus ; the OS calcis ; the scaphoid, to which the bases of the first and second metatarsals are fused; the cuboid, with which are fused the third and fourth metatarsals and the distal dorsal portion of the external cuneiform; the fifth metatarsal. There is no trace of an internal cuneiform. The external cuneiform is represented by a small part of the dorsal aspect fused with the third metatarsal. It is very doubtful whether the middle cuneiform is represented at all, but it is possible that a small prominence in the sole may represent its distal end. This part of the tarsus is very pathological. The line of the joint between the astragalus and the scaphoid on the dorsal aspect is obscured by irregular bony growths, more or le^s interlocking, which probably interfered with motion, though the joint has persisted. The distal borders of the scaphoid cannot be made out accurately. This bone may be said to be amalgamated with the bases of the first and second metatarsals. Not only is there no sign of an internal or middle cuneiform bone on the dorsum, but the distance from the astragalus to the bases of the metatarsals seems if
(530)
D Suppression of the Cuneiform Bones. 531
anything smaller (certainly no greater) than that usually occupied by the scaphoid. On the inner aspect there is a great prolongation of the scaphoid into an uncommonly sharp tuberosity, which appears on the plantar aspect. The line of the joint with the first metatarsal may be followed in a general way, and there is no hint of any remnant of a cuneiform. A rounded ridge in the sole of the foot, from the base of the second metatarsal to the scaphoid, suggests vaguely a small part of a cuneiform, but nothing can be identified certainly.
The culx)id is distinctly shorter than a normal one, and is inextricably mixed with the bases of the third and fourth metatarsals. The reason for accepting a remnant of the external cuneiform bone is furnished by the position of the joint between these bony mas^ses and the scaphoid. This joint, seen from the dorsum, is proximal to the apparent level of the second metatarsal, which would not be the case were the third metatarsal the only element. The joint of the fifth metatarsal shows some pathological changes, especially on
D 532 Thomas Dwight.
the dorsal aspect. It is much more oblique than is normal, and the tuberosity projects laUrally to an uncommon degree. Accurate measurements of any of the metatarsals, with the exception of the fifth, are out of the question ; but it is quite certain that this one is the longest of all. I believe that Pfitzner never obser^^ed this when making his studies of the relative lengths of the metatarsals. The illustrations show that the normal outlines of the foot have been remarkably well preserved, although the outer side of the foot is longer than it should be, and the tarsus forms too small a part of the whole. The most striking defect in the proportions is the great breadth of the foot. This is not caused by any error of articulation, for the nature of the pieces is such as to admit of practically no choice. The length of the articulated foot, measured from the back of the os calcis to the tip of the second toe, is a little over 21 cm., which is certainly small for a male foot. The greatest trans verse breadth, at the proximal end of the phalanges, is a little more than 9 cm., which is abnormally large. It is a case of very advanced "flat foot." The illustrations make further description unnecessary.
An interesting question is — what caused this condition? That the foot is pathological is very clear ; but nothing is more certain than that extraordinary anomalies are associated with pathology in a way that does not allow us to determine what is cause and what is effect. It does not srem possible that this condition is the consequence of a resection in early life. All we can say is that probably the internal and middle cuneiform bones, as well as the greater part of tiie external one, failed to develop; and that the organism, adapting itself to uncommon circumstances, attempted to preserve the general outline of the foot. The underdevelopment of the cuboid, and the obliquity of the joint between it and the fifth metatarsal are elements in this process.
All one has to do to appreciate how successful the effort at reparation has Ix^en is to put together the bones of a foot, leaving out the inner and middle cuneiforms and the greater part of the external one, and to compare the curves made by lines connecting the heads of the metatarsals or of the terminal phalanges with similar lines drawn on these illustrations. The rnore one thinks of it, the more
D Suppression of the Cuneiform Bones. 533
remarkable does it appear that so good a foot should have been formed under the circumstances. Through what agency has this been brought about ? It seems to me that it is a clear instance of the act of the vital principle regulating growth, and repair; the same by which the amputated leg of a newt is reproduced. I incline to agree with Driesch that it should not be called a vital energy, for it is rather something regulating the energy. He would call it entelechy; a something "which bears the end in itself."^ I find no fault with this, but prefer the other term.
Received for publication July 9, 1909.
The Science and Philosophy of the Organism. By Hans Drlescli, Ph.D. Gifford lectures, 1907-08, Vol. T, p. 144.
D A COMPARATIVE STUDY OF THE LYMPHATICO VENOUS COMMUNICATIONS IN ADULT
MAMMALS.
I. Primates, Cabnivora, Rodentia, Uxgulata and Marsupialia.
BY
CHARLES F. W. McCLURE AND, CHARLES F. SILVESTER. From the Laboratory of Comparative Anatomy, Princeton University.
With Three Text-Figures and Ten Plates.
Huntington and McClure^ have shown in the adult eat {Felis domestica) that the communication between the lymphatic system and the systemic veins may normally occur on each side of the body, within either one of two or within two typical districts. These two districts include, approximately, the angle of confluence formed by the union of the external and internal jugular veins (common jugular angle) and the angle of confluence formed by the union of the external jugular^ and subclavian veins (jugulo-subclavian angle). An examination of a large number of adult cats proved conclusively that neither one of these two districts predominates as the place of communication between the lymphatics and the veins, but that either
IIuntiDgton and McClure, The Anatomy and Development of tlie Jugular Lymph Sacs In the Domestic Cat (Fells domestica). A paper read before The Association of American Anatomists in Chicago, in 1907, published in The Anatomical Record, Volume II, 1908, and soon to be published in a more complete form in The American Journal of Anatomy.
"This vein, strictly speaking, is a common jugular vein in the cat, but on account of its large size, as compared with the internal jugular, is usually spoken of as the external jugular vein of which the internal jugular Is a tributary.
(534)
D Lymphatico- Venous Communications. 535
one of the two or both may serve equally in this capacity and for this reason both districts must be regarded as constituting normal points of communication between the lymphatics and the veins.
In following the development of the jugular lymph sacs in the embryonic cat Huntington and McClure were able to establish the basis upon which the duplex character of the lymphatico-venous communication in the adult rests. They found that the right as
Internal J
Lymph Sao
JagaUur .
Juguur V
SubolATian Thyrootnri
Lympluuio SuboUTian ,
Innomuate V
Text-fig. I. — A reconstruction of the left jugular lymph sac of a 11 mm. cat embryo (Felig domestica) showing the relations of the thyrocervical artery to the jugular and subclavian approaches through which the two typical adult communications are established between the lymphatics and the veins. Ventral view. Drawn from a reconstruction made by Huntington and McClure after the method of Born.
well as the left jugular lymph sac in the embryonic cat invariably presents two caudally directed processes or prolongations which they termed, respectively, the Jugular and Subclavian approaches (Textfig. I). These two processes, on each side of the body, are directed
D 536 Charles F. W. McClure and Charles F. Silvester.
toward and approach the district of the common jugular angle and the district of the jugulo-subclavian angle, respectively, and they observed that it is through either one of the two or through both of these processes that the adult communication is established, a circumstance which accounts not only for the presence of a double communication in the adult cat but also establishes it as a character of morphological significance.
In view of the uniform conditions which prevail in the adult domestic cat concerning the presence of two typical districts of lymphatico-venous communication on each side of the body, the present writers have undertaken to determine to what extent this same uniformity may prevail in adult mammals in general.
We have thus far examined twenty-five (25) species distributed among fifty (50) adult mammals (24 primates, 4 carnivora, 12 rodents, 5 ungulates and 5 marsupials). These mammals Avere chosen at random from the Princeton Collection so that the conditions observed in them represent fairly well the average conditions which one might expect to find in any other similar group chosen in the same manner. The lymphatic system of each mammal was injected with gelatine and then carefully dissected out in the appropriate regions on each side of the body. A drawing to scale was made of each dissection to facilitate comparison. All of the figures in this paper therefore represent accurately the arrangement of the lymphatics as met with in the regions of communication and it is worthy of notice that the lymphatics present a marked variability, more so than the veins, not only in the different species examined but among different members of the same species. These variations will not be dealt with to any extent in the present paper except in so far as it becomes necessary to speak of them in connection with the communications which exist between the lymphatics and the veins.
We may state at the beginning that we are warranted in drawing the conclusion from the adult mammals thus far examined that the lymphatic system normally communicates with the veins in these forms as in the adult cat, either at one of two or at two typical districts (common jugular and jugulo-subclavian districts) and that a commimication at the two typical districts is the commonest of theIC
D D Lymphatico- Venous Communications.
537
three possibilities which may normally occur on either side of the body. This is clearly .shown in the following table (Table I) in which it is seen that a communication between the lymphatics and the veins occurred at the two typical districts on the right side of the body in sixty-two (62) per cent and on the left side in seventyfour (74) per cent of the mammals examined; also, when a communication was present, on either side, at only one of the two typical districts, it occurred more frequently at the common jugular than at the jugulo-subclavian district.
TABLE I,
Showing the Relative Frequency with which the Lymphatico- venous ck>mmunicati0n8 occub on each side of the body at ettheb one of the two ob at both of the typical distbicts of communication in the Fifty Mammals undeb Consideration.
Communication at Common Jugular District only. . .
Communication at JuguloSubclavian District only. .
Right Side.
Left Side.
2 ' .2
t ! g
5 «
1 3
2;
Communication at both
Districts ;14' 3 8' 2 4 31 ! 62 17 ' 4
— —
c
a> &»
t ? I •= . ft
S , "O ) ^ I «  t ' O C I t
li
1 116 32 I 7 01 3 2
,12 ' 24
3 6' O' 1 Oi 0' 1 , 2
I I 1
81 3 5
37 74
Text-fig. II is a diagram of the precaval system of veins showing the two typical districts of lymphatico-venous communication, encircled by rings, which are met with on each side of the body. Since we have found that the general plan of the communication is fimdamentally the same on each side of the body, in that it normally occurs at either one of the two or at both of the typical districts of communication (Table I), our interest has been largely centered upon the determination of the combinations in which the communications may occur in the fifty mammals examined when both sides of the
D 538
Charles F. W. McClure and Charles F. Silvester.
body are taken into consideration. Since a communication may be normally established in one of three ways on each side of the body, it is evident, when both sides of the body are considered, that the lymphatico-venous communications may occur in nine possible combinations and that each combination may be regarded as a type of
Zai«rB«l Jncater V.
«— @i
Text-fio. II. A diagram of tlie precaval system of veins showing the two typical districts of lymphatico-veiious communication on each side of the body and the nine possible combinations in which communications may occur when both aides of the body are taken into consideration. Ventral view.
communication which characterizes the lymphatico-venous communication of a particular individual.
Each of the nine possible combinations is indicated in Text-fig. II by a series of arrows which radiate from a small circle enclosing the Roman numeral (I-IX) applied to the combination and is also
D Lymphatico- Venous Communications.
539
TABLE II.
Showino the Nine Possible Combinations (Types of Lymphatico- venous Communication) in which Lymphatico-venous Communications may be Normally Established in an Individual when Both Sides of the Body abe taken into Consideration.
Right Side
Left Side
TvnA Common Jugular Jugulo-Sub- I Common Jugular Jugulo-Sub^' District clavlan District, i District. I clavlan District.
I.
TAP
II.
TAP
III. ,
TAP
1 IV. j
V. ■
TAP
VI.
TAP
VII. 1
VIII.
IX.
TAP
TAP
TAP TAP
TAP TAP TAP
TAP TAP TAP TAP TAP
TAP
TAP
TAP TAP
TAP
TAP TAP
Tlie word TAP, under the district designated, indicates the presence of a communication at this district between the lymphatics and the veins.
TABLE III.
Showing the Distribution among the Fifty Mammals Examined of the Nine Possible Combinations or Types of Lymphatico-venous Communication which may be Normally Established in an Individual.
Type.
Total
Primates.
Carnivora 3
Rodentla.
12
8
5
2
3
1
2
2
1
1
24
4
12
Marsu
1 Number and Percentage
nilata.
pialia.
4
of Ind
ivid per
uals.
2
29 or 58
cent.
2
1 9 or 18
1
1
6 or 12
2 or 4
2 or 4
1 1 or 2
1 1 or 2
'
5
'
' 50
D 540 Charles F. W. McClure and Charles F. Silvester.
shown in Table II, in which the word tap indicates the presence of a communication under the district of communication designated.
The following figures illustrate examples of the diflFerent types of lymphatico- venous communication as met with among the fifty mammals examined :
Type I, Figs. 6, PI. Ill (Papio porcarius), 16, PL VI (Putorius vison), 22, PL VII (Cavia porcellus), 26, PL VIII (Sus scrofa domestica) an'd 31, PL X (Didelphys virginiana) .
Type II, Figs. 12, PL V (Anthropopithecus troglodytes) y 21, PL VII {Lepus cuniculus) and 27, PL IX {Sus scrofa domestica).
Type III, Figs. 5, PL II {Papio anubis), 15, PL VI (Canis familians) and 30, PL IX (Didelphys virginiana).
Type IV, Figs. 4, PL II (Papio anubis) and 1, PL I {Nycticebus tardigradus) .
Type V, Figs. 13, PL V {Anthropopithecus troglodytes)^ and 8, PL III (Macacus rhesus).
Type VI, Fig. 19, PL VII (Lepus cuniculus).
Type VII, Fig. 20, PL VII (Lepus cuniculus).
As shown in Table III the lymphatico-venous communication of every mammal examined fell within one of these nine combinations (Types I-IX). This circumstance, together with the fact that in twenty-nine (29) individuals or fifty-eight (58) per cent of those examined (Table III) the communication occurred on both sides of the body at the two typical districts of communication, and that this type of communication was commonly met with in each of the five orders of mammals examined (Type I, see Text-fig. II and Table III), indicates that the embryonic basis for the establishment of two typical communications on each side of the body must be fundamentally and potentially the same in the fifty mammals examined by us as that described by Huntington and McClure for the domestic cat. Although our present deductions do not lead us beyond a consideration of the conditions observed in the fifty mammals (25 species) it is evident, if this conception of two primary and
■It is significant to note in the two chimpanzees examined, in which the precaval system of veins resembles that in man, that Types II and V are represented.
D Lymphatico- Venous Communications. 541
typical districts of communication on each side of the body can be generalized for mammals as a whole, that a consistent description of the adult lymphatico-venous communications should rest upon a morphological interpretation of their development, and not upon the ill-defined and variable conditions which are at present described in works of anatomy as constituting the points at which the lymphatics communicate with the veins.
It is interesting to note that Type VIII, in which a communication occurs on both sides of the body only at the jugulo-subclavian district (angle of confluence formed by the union of the external jugular and subclavian veins), a region commonly assigned by anatomists as the point at which the thoracic and right lymphatic ducts tap the veins, vxis not met with in a single one of the mammals examined.
As shown in Table I and Table III, when a communication is present on each side of the body at only one of the two typical districts it is usually found at the common jugular (Type II) and not at the jugulo-subclavian district.
The assignment of the jugulo-subclavian angle as the point at which in general the lymphatics communicate with the veins in the adult, appears to us to be a correct interpretation for the cat and for the mammals we have thus far examined, only in the sense that the two districts of confluence formed by the union of the external and internal jugular and by the union of the external jugular and subclavian veins, respectively, be regarded as constituting a single district of communication.
Tables IV to VIII, inclusive, show in tabulated form the different species of mammals examined by us as well as the type of lymphatico-venous communication presented by each individual.'*
The word tap in each column, under the district designated, indicates the presence of a communication at this district between the lymphatics and the veins, while the absence of the word tap indicates that a communication is wanting.
The number after the sex sign of each species indicates the cata
The nomenclature of the species mentioned in this paper follows that given in Trouessart's Catalogus Mammalium, Quinquennale Supplement. 1904.
D 642
Charles F. W. McClure and Charles F. Silvester.
TABLE IV.— PRIMATES.
Nyciicebus tardigradus
9 2374 (Fig. l.PLI.).... Callithrix jacchus
9 2457
Cebus capucinus
9 2481 (Fig.2, PL I.)... Cehu8 hypoleucus
9 2472
Ateles hybridua
^^2433
Ateles hybridua
c?2435
Ateles vellerosua
9 2476 (Fig. 3, PI. I.)... Papio anubis
9 2368 (Fig. 4, PI. II.).. Papio anubis
c^ 2432 (Fig. 5, PI. II.) . . Papio porcarius
d' 2453 (Fig. 6, PI. III.) . Papio porcarius
d2\m
Macacus speciosus
d 2376 (Fig. 7, PI. III.) . Ma>cacu8 irhestis
9 2487 (Fig. 8, PL III.) . Afacacus wmestrinus
d'2458(Fig. 9, PI. IV.).. Alacaciis nemestrinus
9 2459
Macacus nemestrinus
d* 2461
Macacus nemestrinus
d 2483
Cercocfbus fuliginosus
9 2394
Cercopithecu^ callUrichus
d 2434
Cercopithocus cMlitrich u s
d 2464 (Fig. 10, PI. IV.). Cercopithecus cnllitrichus
9 2477(Fig. 11,P1. V.).. Cercopithecus cnllitrichus
d 2478
Anthropopithrnis troglodytes
d2467(Fig. 12, Pl.V.).. A nthropopithpcus troglodytes
9 2468(Fie. 13, Pl.V.)..
Right Side.
Type.
Common Jugular District.
IV
I
TAP
I
TAP
I
TAP
II
TAP
III
TAP
I
TAP
IV
III
TAP
I
TAP
I
TAP
II
TAP
V
TAP
II
TAP
I
TAP
III
TAP
I
TAP
II
TAP
I
TAP
I
TAP
I
TAP
I
TAP
II
TAP
V
TAP
Jugulo Subclavian
District.
TAP TAP TAP TAP
TAP TAP
TAP TAP
TAP
TAP
TAP
TAP TAP TAP
TAP
TAP
Left Side.
Common Jugular IHstrict.
TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP
Jugalo Subclavian
District.
TAP TAP TAP TAP
TAP TAP TAP TAP TAP TAP
TAP TAP TAP
TAP TAP TAP TAP
D Lymphatico- Venous Communications.
543
TABLE v.— CARNIVORA.
Type.
Right Side.
Left Side.
Common Jugular DiBtriot.
TAP TAP TAP TAP
Jugulo Subclavian
District.
Common 1 Jugular 1 District.
TAP TAP
TAP
1
TAP
Jugulo Subclavian
District.
Felis domestica
d'2452(Fig. 14,P1.V.).. Canis familiaris
$2451 (Fig. 15, PI. VI.). Putorius vison
6^2384 (Fig. 16, PL VI.). Mephitis putida
6^2362 (Fig. 17, PL VI.).
I III
I I
TAP 1
TAP TAP
TAP TAP TAP TAP
TABLE VI.— RODENTIA.
Right Side.
Lepus cunictUus
(^2363 (Fig. 18, PL VII.)., Lepus cuniculus
(5^2364 (Fig. 19, PL VII.). Lepus cuniculus
d^2366 (Fig. 20, PL VII.). Lepus cuniculus
6^2367
Lepus cuniculus
$2431 (Fig, 21, PL VIL). Cavia porcellus
(^2359
Cavia porcellus
6^2360 (Fig 22, PL VII.). Fiber ziheihicus
d*2361
Fiber ziheihicus
(^2365 (Fig. 23, PL VIII.). Fiber zibethicus
$2395
Marmota monax
$2469 (Fig. 24, PL VIII.). Seiurus hudsonius
$2466 (Fig. 25, PL VIII.).
Type. ,
Common Jugular District.
TAP TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP !
TAP !
Jugulo Subclavian
District.
TAP
TAP TAP
TAP TAP
TAP TAP TAP TAP
Left Side.
Common Jugular District.
Jugulo Subclavian
District.
TAP
1
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
TAP
D 544 Charles F. W. McClure and Charles F. Silvester.
TABLE VII.— UNGULATA.
! Type.
Su8 scrofa domestica
9 2436 (Fig. 26, PI. VIII.). Sus scrofa domestica
9 2437 (Fig. 27, PI. IX.) . Sti8 scrofa domestica
92438
Sus scrofa domestica
6^2439
Stis scrofa domestica
9 2441 (Fig. 28, PI. IX.)..
I I
I "
I III
I II
1 I
Richt Side.
Common Jugidar District.
TAP TAP TAP TAP TAP
Juinilo Subolavi&n
District.
Left Side.
TAP
TAP
Common Jugular District.
TAP TAP TAP TAP TAP
Juffulo Subclavian
IMstrict.
TAP
TAP
TAP
TABLE VIII.— MARSUPIALIA.
Type
Riffht Side.
j Left Side.
Common Jugular District.
Jugulo Subclavian
District.
Common 1 Jugular 1 District.
Jugulo Subeiavian
District.
Didelphys virginiana
d^2388(Fig. 29,P1.IX.)... Didelphys virginiana
^91
TAP TAP
TAP TAP
TAP TAP
TAP
TAP
TAP
! TAP
TAP
1
TAP TAP
Didelphys virginiana
9 96 (Fig. 30, PI. IX.).... Didelphys virginiana
990
III TAP I TAP
I 1 TAP
TAP TAP
Did4phys virginiana
d^5r(Fig 31,P1.X.)
TAP
logue number of the individual in the Princeton Collection. The individuals figured in this paper are also designated in these tables.
Before proct^eding to a detailed description of the lymphaticovcnous communications observed in the fifty mammals, we will first consider the general character of the two typical districts of lymphatico-venous communication.
Text-fig. Ill is a composite diagram of the prccaval system of veins constructed on the basis of the conditions actually observed in the fiftv mammals under consideration and should be constantly referred to in connection wath the following description of the external and internal jugular and cephalic veins.
D Lymphatico- Venous Communications.
545
1. The External and Internal Jugular Veins.
The external jugular may be larger (Fig. 16, PI. VI) or smaller (Fig. 12, PI. V) than the internal jugular vein, or, of practically the same size (Fig. 5, PI. II).
The common jugular district of lymphatico-venous communication may lie on the same level and in close proximity to the jugulo-sub
RIOHT
Exteraa.1 Jugular V
Internal Jugular V
LEFT External Jugular V
Cephalio V.
Ciavielo
Ccpbalio V.
"Clavicle
Text-fig. III. — A composite diagram of the precaval system of veins constructed on the basis of the conditions observed in the fifty mammals examined and with especial reference to the relations of the two typical districts of lymphatico-venous communication to each other. Ventral view.
clavian district as in Papio porcarius (Fig. 6, PI. Ill) or, as is usually the case in the domestic cat, it may lie somewhat cranial to the jugulo-subclavian district as shown on the right side of Fig. 14 (PI. V) and on the right side of Text-fig. III. In either case, however, the two districts of communication are separated from each other by the external jugular vein.
In the domestic cat the internal jugular vein at times gives up
D 540 Charles F. W. McClure and Charles F. Silvester.
its original connection with the external jugular and then drains into the innominate through the inferior thyroid vein. In a case obser\'ed by us in which this occurred (Fig. 14, PI. V, left side), the common jugular district of lyraphatico-venous communication was not transferred to the new angle of confluence formed by the union of the inferior thyroid and innominate veins but remained on the external jugular at the point where, as on the right side of the same individual (Fig. 14, P1..V, right side), the internal jugular normally joins the external jugular vein.
2. The External Jugular and Cephalic Veins.
As is well known, the cephalic vein presents considerable variability in its relations to the external jugular and subclavian veins, not only in mammals in general but even upon opposite sides of the same individual. The complex of vessels connected with the external jugular and subclavian veins on both sides of Text-fig. III. represents a composite picture of the conditions observed in the fifty mammals examined by us and is an attempt to explain, from the standpoint of comparative anatomy, the variable conditions of the cephalic vein, as well as those sometimes presented by the external jugular, the transverse scapular and deep transverse scapular veins. One might infer from a study of comparative anatomy that this complex of veins may possibly represent a ground-plan arrangement and that the elements of which it is composed are capable of serving in variable capacities, not only in different individuals, but even upon opposite sides of the same individual.
In explanation of the basis upon which the above observations are made the following description of the conditions actually met with, to be compared with the diagram (Text-fig. Ill), is given.
One of the commonest terminations of the cephalic vein met with is its connection with the external jugular, as in Felis dome^tica (Fig. 14, PI. V), Cams familiaris (Fig. 15, PI. VI), Putorius vison (Fig. 16, PI. VI), Fiber zihethicus (Fig. 23, PI. VIII), Cat>ia parceUus (Fig. 22, PI. VII), and Sits scrofa dom^stica (Fig. 26, PI. VIII), where it is commonly established through the vessel C or D in Text-fig. III. It may be formed, as in Maca^us rhesus (Fig. 8,
D Lymphatico- Venous Communications. 547
PL III), Cercopithecus callitrichus (Fig. 11, PI. V) and Cebus capucinus (Fig. 2, PI. I), through the retention of the vessels B and D in Text-fig. Ill, as is also the case in Didelphys virginiana (Fig. 31, PI. X, left side). It may also be formed in Didelphys virginiana (Fig. 31, PL X, right side), as is more commonly the case,^ through the retention of the vessels A and D in Text-fig. III. In Sciurus hudsoniiLs (Fig. 25, PL VIII) it may be formed through the retention of the vessel C in Text-fig. Ill, but vessels B and D may also be present where they, together with the external jugular vein, form a loop or ring through which the clavicle passes. In one specimen of Ateles vellerosus examined (Fig. 3, PL I), in which there is an asynmietrical arrangement of the veins on opposite sides, the cephalic vein is formed through the retention of the vessel A in Text-fig. Ill on the right side and by the vessel B on the left. Although the conditions observed in Ateles are probably abnormal, they sen-e as a good general illustration of the variability manifested by termination of the cephalic vein.
The elements which compose the complex of veins ordinarily entering into the formation of the cephalic also appear to be capable of functioning as the terminals of veins other than the cephalic. For example, in Lepus cunicuhis (Fig. 20, PL VII) the transverse scapular vein appears to have been established through the vessel B in Text-fig. Ill which in Ateles vellerosus (Fig. 3, PL I, left side) and in part in Macacus rhesus (Fig. 8, PL III) constitutes the terminal of the cephalic vein. Also in Marmota monax (Fig. 24, PL VIII), as shown by its relation to the clavicle, the external jugular vein has largely transferred its drainage from its conventional pathway to the vessel B in Text-fig. Ill which now functions as the chief terminal of the external jugular vein.
At first sight one might regard the boundaries of the two typical districts of lymphatico-venous communication as being fundamentally modified in accordance with the variations presented by the veins in the region of the lymphatico-venous communications. Such does
•^C. F. W. McClure, A Contribution to the Anatomy and Development of the Venous System in Didelphys marsuplalis. Part I, Anatomy. Amer. Jour, of Anatomy, Vol. II, 1903 (see Fig. II, p. 377).
D 548 (^harles F. W. McClure and Charles F.. Silvester.
not appear to be the case, however, since the primary relations established by the union of the external and internal jugulars and by the external jugular and subclavian veins, respectively, definitely mark out the two typical districts of communication as evidenced by the constancy with which communications occur in connection with these districts, regardless of the variation presented by the veins.
We pass now to a consideration of the general character of the lymphatico-venous communications as met with in the fifty mammals examined.
When a communication occurred on either side, at either one of the two typical districts, it was usually single in character as shown in Table IX. In only a few instances were the lymphatics found to communicate with the veins within either of the two typical districts by more than one opening. A multiple communication between the lymphatics and the veins was found at the common jugular district of communication in Ateles vellerosus (Fig. 3, PI. I, right side), in Cercopithecus callitrichus (Fig. 11, PI. V, both sides), in Felis domestica {Y\g. 14, PI. V, right side), in Macacus nemestriuus (Fig. 9, PL IV, both sides) and the the jugulo-subclavian district of communication in Cards familiaris (Fig. 15, PI. VI, left side) and in C ercopiihecus callitrichus (Fig. 10, PI. IV, right side).
As shown in the following table, only twelve (12) instances of a multiple communication at the two typical districts were met with and it occurred more frequently on the right than on the left side of the body.
One hundred and seventy-eight (178) points of communication between the lymphatics and the veins were observed by us on both sides of the body in the fifty mammals under consideration (89 on each side). Of these, one hundred and forty-two (142) were found either at the angles of confluence formed by the union of the external and internal jugular and by the union of the external jugular and subclavian veins, respectively, or w-ere included within these two angles, as illustrated by Figs. 12, PI. V, 13, PL V {Anthropopithecus troglodytes), 8, PL I (Ateles vellerosus), 7, PL III
D Lymphatico- Venous Communications.
549
{Macacus speciosus), 8, . PI. Ill (Macacus rhesus), 1, PI. I {Nyticehus tardigradus) y 4, PL II, 5, PL II (Papio anubis), 22, PL VII (Cavia porcellus), 19, PL VII, 20, PL VII, 21, PL VII (Lepus cuniculus), 24, PL VIII (Marmota monax), 25, PL VIII {Sciums hudsonius) and 27, PL IX (Sus scrofa domestica).
TABLE IX. Showing the Pbedominance of a Single over a Multh^le Communication
AT each of the two TYPICAL DlSTMCfTS OF LyMPHATICO-VENOUS COMMUNICATION.
Right Side.
Left Side.
Single Communication at Common Jugular District 19
Multiple Communication at Common Jugular District
Communication Wanting at Common Jugular District
Total.
11! 3 5
[ I 2
4 12 1 5; 5
I I
! I
o I 6
41 22 4 11
6i' 2!
3|. ij^ 60 ' 24 4 I 12
5i 6 47 2
5 6
1 50
Single Communication at Jugulo- 1
Subclavian District 13 ' 3 9 2,4
I , I
Multiple Communication at Jugulo-' ! i
tipU
UDCl
Subclavian District 3
i 1
Communication Wanting at Jugulo- I
Subclavian District ISil 3 31
Total.
I 24 4 I 12 . 6 5
17
1 3 9
1
3
5
37 1
7
3
2
12
24
4 12
i 5 5
50
Three (3) points of communication met with did not fall either within the angle of confluence formed by the union of the external and internal jugular nor within the angle formed by the union of the external jugular and subclavian veins, but, as in Figs. 2, PI. I {Cehus capucinus, right side), 28, PI". IX (Sus scrofa domestica.
D 550 Charles F. W. :McClure and Charles F. Silvester.
left side) and 14, PL V {Felts domestica, right side), they occurred on the veins slightly caudal to the angle of venous confluence (caudal to the common jugular angle in Cebus and Felis, and to the jugulosubclavian angle in Sus).
Also, in addition to these three points of conununication just mentioned, thirty-three (33) others were met with which did not fall within the common jugular nor jugulo-subclavian angles but which were dorsally or ventrally situated on the veins in dose proximity to either one of the two of these angles.
Of these dorsal and ventral communications between the lymphatics and the veins, the former proved to be the more common of the two.
A dorsal conmiunication between the lymphatics and the veins on both sides of the body at the conmion jugular district of communication is shown in Figs. 15, PI. VI {Cards familiaris) and 17, PL VI (Mephitis putida). A dorsal communication between the lymphatics and the veins on the right side of the body at the common jugular district of communication is shown in Figs. 10, PL IV {Cercopithecus callitrichus) and 9, PL IV {Macacus nemestrinus) and at the jugulo-subclavian district of conmaunication in Fig. 23. PL VIII (Fiber zibethicus). A dorsal communication between the lymphatics and the veins on the left side of the body at the jugulosubclavian district of communication is shown in Figs. 29, PL IX (Didelphys virginiana) and 26, PL VIII (Sus scrofa domeslica).
A ventral communication between the lymphatics and the veins on both sides of the body at the common jugular district of communication is shown in Figs. 11, PL V (Cercopithecus callitrichus) and at the jugulo-subclavian district in Fig. 17, PL VI (Mephitis putida). A ventral communication between the lymphatics and the veins on the left side of the body at the jugulo-subclavian district of communication is shown in Fig. 6, PL III (Papio porcarius) and on the right side of the body in Fig. 11, PL V (Cercopithecus cailitrichus) .
In consideration of the large number of commimications observed within the common jugular and jugulo-subclavian angles (142), the presence of these thirty-six apparently variant forms appears to
D Lymphatico- Venous Communications. 551
find its explanation in the circumstances that the communications established between the embryonic jugular lymph sac and the veins are not confined exclusively within these two angles of venous confluence but may vary about the same in a sphere which we have designated a district of communication (Text-figs. II and III). The circumstance that angle, dorsal, and ventral communications may be found in the same individual, in which they hold definite relations to either one of the two typical angles of venous confluence and that, in some cases, dorsal and ventral communications are alone present (Fig. 17, PI. VI), seems conclusive evidence that all of the points of communication observed by us between the lymphatics and the veins must have been established in the embryo in fundamentally the same manner as in the domestic cat and in definite relation to two typical districts of commimication.
Received for pubUcation July 9, 1909.
D EXPLANATION OF PLATES I TO X.
Figs. 1 to 31, inclusive, were drawn to scale from dissections of adult mammals and represent ventral views of the veins and lymphatic vessels in the regions where the lymphatics communicate with the veins.
The veins are draAvn in outline, the lymphatics are colored. The word TAP indicates a point at which the lymphatics communicate v^th the systemic veins.
The name of the species represented is given under each figure while a complete list of the mammals dissected and studied in connection with this paper may be found in Tables TV, V, VI, VTI and VIII.
D D D D LYMPH ATICO-VENOUS COMMUNICATIONS. CHAHLES F. W. MCCLURB AND CHARLES F. SILVESTER.
BiaaT
Int«maL Jugular V
i
Cepbaj
SuboUTian v
^
AiygM V.
Fio. 1 (Type IV)
Slow Loris ?
yifcticchus tanlipradus, Linn.
TOMICAL RECORD. VOL. Ill, NO. 10.
D PLATE I.
BIQBT External Jugular V
Internal Jugular V
Ceptaalio V
LEFT External Jugular V
Fig. 2 (Type I)
Capuchin Monkey $
Cchus capucinus, Linn.
AIQflT External Jugular V
Cei
Internal Jugular V
/
LEFT External Jugular V
8u
\
Thoraoio Duot
SubolaTian V
'Bronchomediastinal Trunk
Fig. 3 (Type I) Spider Monkey $ Ateles vellerosus, Gray
D D D LYMPH ATICO-VENOUS COM MUNICATIONS. CHARLES F. W. MCCLURE AND CHARLES F. SILVESTER.
Fic. 4 (Type IV)
Aiiubis Baboon 5
Papio anuhis F. Cuv.
The Anatomical Record. — Vol. III. No. 10.
D BIOflT External Jogalar V
Internal Jus^ilar V
LEFT
qplUfcUO V.
»nl
Aaygos V
Thoraoio Dnot.
Thoracic Duct.
Fig. 5 (Type III)
Auubis Baboon (^
Papio antihis, F. Cuv.
D D D LYMPH ATICO-VENOUS COM M UNICATI0N8. CHARLKS F. W. MCOLl'RE AND CHARLES F. SILVESTER.
Fig. 6 (Type I)
Chacama Baboon J
Papio porcarius, Bodd.
/
TfaoTMsie Doc
Fig. I
JapaiM
Thb Axatomical Record. — Vol. Ill, No. 10.
D PLATE III.
Internal Jugnlar V
aiOHT External Jagular V.
LEFT External Jugular V.
Thoracic Duct.
II)
C?
«, Cuv.
Fig. 8 (Type V)
Rhesus Monkey J
Macacus rhesus, Audebert
Cephalic V
D D D D D LYMPHATICO-VENOUS COMMUNICATIONS. CHARLES F. W. MCCLCRE AND CHARLES F. SILVESTER.
Fig. 4 (Type IV)
Anubis Baboon 5
Papio anubis F. Ciiv.
Tub Anatomical Uecord. — Vol. III. No. 10.
D PLATE II.
RIOflT Bztenud JogaUu* V
Internal Jugular V
\ _
LBFT External Jugular V
BobolaTiaa 1
Thoraoio Dnot.
Tboraoio Duot
Fig. 5 (Type III)
Auubis Babo(3ii ^
Papio anuhis, F. Cuv.
D D D LYMPIIATICO-VENOUS COM U UNICATIONS. CHARLES F. W. MCCLURB AND CHARLES F. SILVESTER.
BIQflT Bztanial Jagalar V
Inumal JusuUr V
Cephalic V.
Fig. 6 (Type I)
Chacairia Baboon J
Papio porcariHs, Bodd,
/
Thoracic Dtt(
Tub Anatomical Record. — Vol. Ill, No. 10.
Fig. 7
JapaD<
Miicacus «
D PLATE III.
Internal Jugular V
EIGHT External Jugular V.
LEFT External Jugular V.
Thoracic Duct.
II) K«, CuV.
Fig. 8 (Type V)
Rhesus Monkey J
Macacus rhesus, Audebert
Cepbalio T
)igitized by IC
D D LY MPHATICO- VENOUS COM M l X ICATIONS. CHARLES F. W. MCCLURE AND CHARLES P. SILVESTER.
BIOfiT Bxtemal Jugulftr V
IsEFT MxtantalJngalmr V
Fig. 9 (Type II)
PIg-talled Macaque c?
Macacus nemestrinuSy Linn.
The Anatomical Record. — Vol. Ill, No. 10.
D PLATE IV.
Internal Jugular V
BIGHT External Jugular V
LEFT ternal JuguJar T
Subclavian V.
- Thoracic Duel.
Aaygot V.
Fig. 10 (Type I)
Green Monkey J
Cercopithecua callitrichus, Geoflf.
D D D D D LYMPH ATICO-VENOU8 COMMUNICATIONS. CHARLES F. W. MCCLURE AND CHARLES P. SILVESTER.
Exeernol JnguUr V.
Cephalic
P y Extcnial Jogalmr r
SnbcUnaa T.
Seoff.
Internal Jugular V.
RIGHT External Jugular V,
LEFT External Jugnlar V.
Thoracic Duoi.
Fig. 13 (Type V)
Chiiupanzee $
Anthropopithecus troglcHfytes, Linn.
Tham
Aiith
J
"IIB ANATOMICAL RECORD. VOL. Ill, NO. 10.
D Internal Jugular V.
/
LEFT Sztemal JugnUr V.
Subclavian V.
ymph Nodes
VIK
Aorta
(Type II) panzee d iS troglodytes, Linn.
)igitized by IC
D D LYMPHATIC0-VEN0U8 COMMUNICATIONS. C'HABLES F. W. MCCLURE AND CHARLES P. SILVESTER.
aiOBT Sxtonul Jugular V
lAtMiial JagnlAr V.
olftvian V.
o IHiet.
A*JCM V.
-— Aorte
Fig. 16 (Type I)
Mink c?
Putorius vison, Brlsson
'I'HK ANATOMICAL RECORD. VOL. Ill, NO. 10.
D PLATE VI.
RIGHT
B3tt4
LEFT Extornal Jugular V.
Subclavian V.
Thoracic Duct.
'. 15 (Type III)
Dog $ f familiarise Linn.
LEFT
F
Meph
D LYMPHATICO-VENOUS COM M UNICATIONS. CHARLES F. W. MCCLUKK AND CHABLES P. SILVESTER.
BIOBT External Jugular V
LEFT External Jngalar V
Internal Jugular V.
Trans. Sea
Subolan
Internal Jugular V.
BIGHT Ti-ana. Soap. V.
I ^4^ PrMsava
Thoraoio Duct.
Fig. 18 (Type I) Rabbit c? Lcpus cuniculus, Linn. TOMicAL Record,— Vol. Ill, No. 10.
r
alar V
Internal
V uiceniBi
Fig. 19 (Type VI)
Rabbit d
Lepus cwiiculus, Linn.
Subola Thor*
▲sygoa
D Aortaj
Fig. 20 i
Lcpus rutm
PLATE VII.
LEFT
Scapul
BFT rogular \
Fig. 21 (Type II) cephaUo v Rabbit $
^'•^^ .Trana. Scap. V.^^PW* CUniCUlUS, Linil.
Subclavian V.
Precava
LEFT External Jugular V
Cephalic V
h
Lymph Hodes
VII) > Linn.
Subclavian V.
Subclavian V
Thoracic Duot
▲orta
Fig. 22 (Type I)
Guiiiea-Pig ^
Cavia porccUus, Linn.
D D D D D LYMt»MATlCO-VENOUS COM M UNICATHJNS. riiAULRR P. W. MCCLl'RK AND CHARLKS P. SILVESTER.
BIGHT Eztornal Jugular V.
Cepbalio V.
SIGHT External Jngalar V.
Intornal Jugular V
Captaalio V.
Cepbalio V
Fig. 24 (Typk I)
Ground Ilog $
Marmota momix, Llnii
LEFT External Jugular V
Fig. 23 (Type I)
Musk' Rat c?
Fiber zibethUvH, Linn.
Thoraoic Duot
Asygoa V
'TOMicAL Record. — Vol. Ill, No. 10.
D PLATE Vin.
SxternalJ
LETT sternal Jugular V.
Uo V.
Oapha
Subol
BIGHT Sztomal Jugular V
h
LEFl Szternal Jn
Internal Jugular V
A
Cepbalio V.
phaiiov. Fig. 26 (Type I)
Pig 2 S!u8 scrofd domcstica. Gray
Subolaviai
Fig. 25 (Type i) Red Squirrel $ iurus hudsonius, Erxleb.
r
uwrcMJAU J^UO(.
D D D D D LYMPHATICO-VKNOrs COM M INICATIONS.
CHAULKS F. W. McrhritK AM) rilAHLKS F. SILVKSTER.
I.EFT
Internal JagnUr V External JaculAr V
Bnbolai .^
V.
Fig.
rig ?
Su8 8(rofa domes tica. Gray
LBPT BIGHT External Jugular V
Sufc
nidi The Anatomical Kkcord — Vol. 111. No. 10.
D RIGHT Internal Jugular V
J)i<Jeli)hifS rirgiiiiaiia. Km*
Plate IX.
D D I» M ATICO-VEN0U8 COM M UNICATIONS.
ftl^KH F. W, MCCLL'RE AND CHARLKS F. SILVESTER.
Plate X.
BIGiiT BxMnud JofiiUr V
LEFT Bxt«rn«l JoguUr V
liTiole
GUvicl
Sub
Fig. 31 (Type I)
Opossum (J
Didelphys virginiana, Kerr
The anatomical Record. — Vol. Ill, No. 10.
D D D D NOTES.
Doctor Irving Hardesty has been appointed Professor of Anatomy in Tulane University. The department, which formerly included only gross anatomy, will now have charge of histology as well. Professor Hardesty will be assisted by Assistant Professor Henry W. Stiles, M.D., formerly of the University of Michigan ; Assistant Professor Henry Bayou, A.M., M.D., and Mr. H. H. Bullard, A.B., M.S., formerly of the University of Missouri, who will be Instructor in Anatomy. The following physicians will be assistant demonstrators : Dr. Sidney P. Delaup, B.Sc. ; Dr. Marion S. Souchon ; Dr. John F. Oechsner; while Dr. Charles A. Wallbillich, Dr. John F. Points and Dr. M. H. McGuire will be junior assistant demonstrators. Professor Hardesty, Professor Stiles and Mr. Bullard, as well as the technical assistant, Mr. Linstaedt, will give their entire time to the department. Dr. Edmond Souchon has been made Professor Emeritus of Anatomy and Curator of the Museum.
Eichard E. Scammon, A.M. (University of Kansas), has recently been awarded the degree of Doctor of Philosophy by the Faculty of Arts and Sciences of Harvard University, for studies in medical sciences,- particularly in embryology. He is thus the first candidate to avail himself of the new arrangement whereby this degree may be obtained by study and investigation conducted in the Medical School. Dr. Scammon's thesis will be published as the Normentafel zur Entwichlungsgeschichte des Squalus acanthias in Professor KeibePs series.
(553)
D D THE
ANATOMICAL RECORD
Vol. III. NOVEMBER, 1909 No. 11
A NOTE ON THE ORGANIZATION OF THE VENOUS
RETURN WITH ESPECIAL REFERENCE TO
THE ILIAC VEINS.
BY
H. VON W. SCHULTE and FREDERICK TILNEY. From the Anatomical Laboratory of Columbia University,
With EleVek Figures.
This paper is an attempt to formulate a few general propositions having reference to the organization of the venous system as a whole, and further to indicate some of the underlying hydrodynamic factors incident to the formation of the major lines of drainage. Broadly speaking, the veins of the mammal between the peripheral capillaries and the heart fall into two fairly definable regions, a central district of large venous trunks and a distal region of smaller plexiform vessels. The circulation in the adult differs from that of its embryo largely in the reduction of these plexuses to form larger single veins, the zone of plexiform veins retreating farther toward the periphery.
The result of the substitution of large trunks for plexuses is the reduction of the impediment offered to the venous return by surface friction, consequently either a reduction of cardiac work or, the work performed by the heart remaining the same, a more rapid circulation and potentially a higher rate of metabolism.
We conceive that it is the general competency of the circulation as a whole, rather than the topographical situation of the lines of
(555)
D 556 H. von W. Schiilte and Frederick Tilney.
venous drainage, which is of evolutionary significance. Natural \ selection would easily be imagined to operate to destroy an animal whose venous system offered too great a resistance to the flow of the blood, while it is by no means obvious that, given a circulatory competency, the exact topography of a vein can often be of moment to its possessor. The high variability of veins is common knowledge and lends support to this view.
A cursory examination of the variations of the venous system in the three forms most extensively studied, man, the opossum^ and the cat,^ suffices to show that while variations in the situations of the individual veins and even in the topography of the major trunks are wide in range and frequent in occurrence, yet points at which plexus formations replace single veins are subject to relatively little change — ^the anatomic plan varies widely within limits rigidly fixed by physiologic efficiency. It might then fairly be expected that the evolution of the venous system, in its broad outlines, should be in the direction of organization and higher physiological efficiency, rather than the formation of a series of morphologic types. From this standpoint the venous system of the monotremes appears to us a generalized type of low organization, comparable to the embryonic veins of marsupials and placentals.
In Omithorhynchus the plexiform arrangement involves even the postcavflB to the renal level (Figs. 1 and 2). The two vessels are connected dors'ally by massive anastomoses. Traced caudad to about the lumbo-sacral junction each postcava resolves itself into two extensive plexuses, one dorsal and the other ventro-mesial to the psoas minor. At the lateral border of the muscle a wide channel connects the two plexuses ; the dorsal plexus is composed of tributaries, enumerated cephalo-caudad as follows:
1. An ilio-lumbar plexus.
McClure, C. F. W., *03. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialis." Part I. Amer. Jour. Anat, Vol. II, No. 3.
•Darrach, W., '07. "Variations in the Postcava and its tributaries as observed in 605 Examples of the Domestic Cat." Amer. Jour. Anat., Vol. VI, No. 3, page 30.
I
Organization of the Venous Eetum. 557
. ANASTOMOSIS ILIO-LUMBAfl PI iAL PLEXUS
•APHENA P
A FOR PSOAS iPSMORAL PLI APHENOUS PLEXUS
CAUDAL PLEXUS
Fig. 1. Ornithorbynchus paradoxus. From a dissection in the study collection of the Department of Anatomy, Columbia University. Showing the postcavfe and their tributaries Ventral view, semi-diagrammatic. The aorta and branches have been omitted to allow the dorsal anastomoses between the postcavfie to come into view. The psoas minor of the left side Is also omitted.
D Fig. 2. Ornithorhynchus paradoxus. Dorsal view. From a dissection in tlie study collection of tlie Department of Anatomy, Columbia University. After injection the vessels were removed in mass.
D Organization of the Venous Return. 559
2. A large trunk from the dorsum of the thigh (saphena parva).
3. Veins coming from the fat pad of the groin.
4. A femoral plexus.
It is noteworthy that the drainage from the panniculus and the subpannicular fat of the trunk is accomplished by large veins (vide supra 2 and 3), while that from the deeper parts is given by the plexiform vessels accompanying the arteries. The ventro-mesial plexus is composed from without inward of the following plexiform vessels :
1. A deep epigastric which receives a considerable plexus from
the thigh.
2. An internal iliac, receiving the obturator and vesico-pudendal
plexuses.
3. A caudal plexus.
Across the median line the plexuses of the two sides anastomose freely dorsad of the aorta, and ventrally more or less completely across its large branches.
It is, of course, arguable that the circulatory system of Omithorhynchus is not primitive, but highly specialized in adaptation to the animal's semi-aquatic habits. Besembling, as it does, the venous plexuses of the cetacea, though it differs in degree and constitution, no one would deny that it stands in relation to the creature's habits. But it by no means follows that it is highly specialized, since a retention of the embryonic characters in the adult may have as high adaptive value as the development of new characters. In the extensive plexus formation, the thin walls of the vessels and the excess in lumen of the veins over the arteries, we have a picture closely resembling the vessels of the embryos of higher forms, — a system of vessels in which a relatively small column of blood reaches the capillaries through the small and often plexiform arteries, accumulates in the veins and sluggishly returns to the heart. This condition is undoubtedly one of low physiological organization, fitted by the multiplicity of its venous paths to serve as a composite schema of the variants of the venous system in higher mammals. Further in Echidna, which is not an aquatic animal, but little reduction of the plexus has
D 560 H. von W. Schulte and Frederick Tilney.
occurred. It is significant that this reduction affects the postaortic anastomoses.
In turning from the monotreme to the marsupial, we find in the latter an immense advance in the organization of the venous return. Not only the postcava but also the iliac and often the caudal vein are free of plexus formation, though there is not infrequently a remnant of the plexus in the form of "venous islands" in the region of the promontory, yet even these are fewer than in such placental forms as the edentate or even the cat, and they are far less extensive than in cetacea.
If the plexuses of monotremes are primitive, as we take them to be, it becomes a problem to deduce from them the trunk drainage of the marsupials and placentals. A few details of the morphol(^y of the marsupial veins are a necessary preliminary.
In a specimen of Trichosurus (Fig. 3) the cava is formed by the confluence of a number of radially disposed vessels, the ilio-lumbar, external iliac and internal- iliac veins. The left internal iliac receives the caudal. The specimen shows, perhaps, a slight tendency to the formation of a common internal iliac trunk. Compared to this tbe monotreme presents a great excess of vessels in its fan-shaped plexuses, while here we have, as it were, only the ribs of the fan, the intervening web reduced to small tributaries of the major trunks. Kadial hydrodynamic lines have developed and there has followed, as must follow, a reduction of the network. It is obvious that if two converging veins of equal size are connected by a homogeneous reticulum, the blood flows from all parts of the reticulum under the vis-a-tergo of the arteries and the suction through the veins of the cardiac diastole (Fig. 4). It follows that the blood will flow from the center of the reticulum toward the large veins, and that the periphery will have not only to transmit the blood directly reaching its meshes but also to drain the central areas. Its function, therefore, is at a maximum near the large veins, and diminished toward the center where, as it were, a watershed is formed, dividing the reticulum into two drainage areas. The peripheral parts of the plexus persist as small tributaries of the veins favored by the hydrodynamic lines (Fig. 5), and resolve themselves into smaller vessels and capillaries
I
Organization of the Venous Return. 5G1
ILIOLUMBAR VEINS
i EXT. LATERALIS
ILIACA EXT. MEDIALfS
CAUDAL VEIN
FiQ. 3. Trichosurus vulpecula. From a dissection in the study collection of the Department of Anatomy, Columbia University. Postcava and pelvic veins showing radial arrangement
D Fig. 4.
Fig. 5.
D Organization of the Venous Return. 563
as the divide is approached. Our knowledge of the ontogeny of the pelvic vessels in marsupials is unfortunately small, yet it seems fair to argue from the redundancy of fcetal vessels everywhere, that some such reducing factor as we have mentioned is active mechanically in occasioning the substitution of trunk vessels for plexus formation.
The radial arrangement of the pelvic vessels described above appears to be unstable even in Trichosurus. (Fig. 6.) Besides the specimen of Trichosurus figured, it occurs, so far as we are aware, only in Pseudochirus where it is complicated by the presence of venous rings about the large arteries. Elsewhere the arrangement is disturbed by a tendency of adjacent, ultimately confluent trunks to form a conmion vessel of greater or less extent, transforming the V shape of their union into a Y, and giving rise to an apparent distad recession of the angle of union. The trunks thus affected are the external and internal iliacs with the resultant common iliac — an almost constant formation in the Australian marsupial — or the two internal iliacs to produce a common internal iliac as often in Didelphys virginiana. Trichosurus appears as the starting point of these two types, inclining, however, markedly to form a common iliac In either case the result is the same, the reduction of friction and a displacement of the angle of confluence distad. This phenomenon seems capable of mechanical explanation. Given two equal veins inosculating proximally and connected distally with drainage areas which are increasing in size, an increasing venous return demands an increase in the size of the veins. The trunk proximal of the union tends to lie in the prolongation of the axis of the angle of union (Roux). At this point, therefore, the blood stream changes its direction. Its momentum may be decomposed by the parallelogram of forces into a moment acting in the axis of the resulting vessel and a moment at right angles to this, tending to push the walls of the tributaries into closer approximation and to form a spur at the angle of confluence (Fig. 8). Thus more and more the uniting vessels would tend to have their proximal segments parallel, with their walls in apposition. This spur will sustain the pressure of the b'lOod stream upon both sides, which constitutes an abnormal
D 564 H. von W. Schulte and Frederick Tiln^.
Fig. 6. Trichosurus vulpecula. From a dissection in tlie study collection of tlie Department of Anatomy, Columbia University. Showing common iliac type.
D Oi^anization of the Venous Return.
environment for its cells, tending to its ultimate reductionr McMurrich* has reported cases in man of partial persistence of such formations in the iliac veins. Against this mode of accounting for the Y type, an alternative explanation may be argued. It might be held that the recession of the angle was apparent only, that actually a new confluence had been formed by the development of a cross channel through a more distal portion of the reticulum. As will appear subsequently, we are far from denying this possibility, but interpret it as the disturbing result of factors extrinsic to the circulatory system itself, in fact as an example of the establishment of a collateral circulation following interference in a hydrodynamic line (Fig. 9).
Fig. 7.
Fig. 8.
■McMurrich, J. P., *06. "The Occurrence of Congenital Adhesions In the Common Iliac Veins and their Relation to Thrombosis of the Femoral and Iliac Veins." Brit. Med. Jour., II, page 1699.
H. von W. Schulte and Frederick Tilney.
In our figure, should such a factor operate upon the segment B tending to its destruction, flow would be reversed in the reticulum previously draining into it, and a new channel such as C would result from the enlargement of portions of the reticulum responding to the increased function required below the obstacle. But apart from such external interference, the line B would tend to be retained, for the inlet from B' is freer into B which is in line with it, than into the diverging channel C. A good illustration of the displacement of the angle distad is afforded by the vessels in the blastoderm of the chick. The caudal vein in marsupials is subject to a wider range of variation than the iliac vessels. In Phascolomys (Fig. 10) in addition to a mouth in the left common iliac it is connected by three pairs of transverse branches with the internal iliacs^ forming a sort of grill pattern. In one individual of Phascolarctos a closely similar arrangement was found. In both of these forms the tail is rudimentary. In other marsupials it usually opens by a single mouth into one or other common or internal iliac, only occasionally retaining the remnant of a plexus in multiple points* of debouchment. Followed distad it soon breaks up (usually at the root of the tail) into a plexus surrounding the caudal artery. A distinction can thus be drawn between the large-tailed forms and those having short tails, in reference to the caudal vein, which in the latter forms retains more of its plexiform character. Evidently the size of the drainage area, the volume of blood to be transmitted, is the determining' factor in the evolution of trunk veins as against plexuses. The existence of traces of plexus formation in some individuals of the Macropodidse does not militate against this view, as here a large part of the caudal return is provided by subcutaneous channels.
Fig. 9.
In general the larger the area drained — the greater the length of the trunk in the proximal portion of its drainage line — ^the farther distal is the point at which the plexuses occur. A familiar example is the comparison of the V. femoralis and the V. poplitea in man with his Vv. brachiales which are plexiform. The caudal vein is, however, a more convincing example, as here such disturbing factors as might result from the upright position of man may be excluded.
The arrangements of the common and external iliac veins among the marsupials are of considerable theoretic importance. Two types may be distinguished in the relation of the vein and artery. In Didelphys* the external iliac vein lies lateral to the artery. In the Australian marsupial the leg is drained by channels lying mesial to the artery (Figs. 3 and 10), external iliac and common iliac veins. Intermediate forms, however, occur. In Trichosurus and Phascolomys, for example, there is sometimes in addition to the large critally placed vessel a smaller lateral one, varying in development and inosculating distally with the external iliac near the groin, but not at a constant level. It receives tributaries from the psoasiliacus and may show a plexiform character. In the elephant (Darrach) double external iliacs accompany the artery, one lateral, one mesial. The same arrangement occurs in the 20 mm. cat embryo (Huntington). In monotremes a plexus accompanies the arteries. The evidence, while admitted fragmentary, appears to us to warrant the conclusion that the external iliac vein results from the solution of a plexus.
McClure, C. F. W., '03. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialis." Part I, Amer. Jour. Anat., Vol. II, No. 3. (See plates.)
Fig. 10. Phascolomys Mitchell!. From a. dissection in the study collection of the Department of Anatomy, Ck>lumbia University Showing vena iliaca externa lateralis, vena iliaca externa medialis and grill pattern of caudal veins.
While in the case of the internal iliac vein, reduplication of the vessel has not been observed among the marsupials, so far as we are aware, yet the variety in its relation to the artery — it may be dorsal or ventral, lateral or mesial — su^ests a similar origin. And again the monotreme has the plexus.
The corollary follows that these homonymous great veins are not morphological equivalents; the V. iliaca externa lateralis is not morphologically the same as the V. iliaca externa medialis, but results from a specialization of a different area of plexus. The veins are homodynamous, agreeing in function, that is in the drainage of similar areas ; and it thud appears that the anatomical names of veins designate not morphological but physiological units. The hydrodynamic line of drainage is far more constant than the morphological structures which compose it, and unconsciously this drainage line has been the subject of our nomenclature. A more striking illustration is afforded by the term postcava, as already pointed out by Dwight' and Lewis.® This vessel is composed of morphological, distinctly defined elements, sinus venosus, vena hepatica communis, hepatic sinusoids, subcardinal, supracardinal and postcardinal veins. In the marsupial the cardinal collateral replaces the supracardinal in this list. The post-renal element may be cardinal, supracardinal or cardinal collateral ; it may be double or single to the right or left in front of the aorta. Apart from its parallelism to the aorta, its only constant character is that it drains the tail, the hinder extremity and one or both of the gonads according to its site, at one side or in front of the aorta. It is obvious that we are dealing with a definite line and area of drainage, which may be aflFected indifferently well by any one of a series of vessels. The term postcava only indicates this hydrodynamic line. The case here is essentially the same as we have attempted to show for the external iliac. A venous plexus surrounding the aorta is antecedent to the formation of trunk vessels. The variously named cardinals are merely dilated portions of chis reticulum along the major hydrodynamic lines, which, responding to the large volume of blood they transmit, dominate the picture. The smaller transverse channels were long treated as of little morphological importance, except where from external factors in the course of development, the flow became retarded in one of the longitudinal vessels, when they entered the field of consciousness under the term anastomosis as a means of accounting for the emergence or enlargement of another longitudinal line. The early investigators of the development of the venous system rarely figured these plexuses, and their schemata showing only the longitudinal hydrodynamic lines, still illuminate our text-books and adumbrate the subject. Recent workers give more complete figures (Lewis,® ; Miller,® ; Huntington and McClure,®).
•Dwight, Thomas, '01. "What constitutes the Inferior Cava." Anat. Anzelg., Vol. XIX, pages 29-30.
•Lewis, F. T., *02. "The Development of the Vena Cava Inferior.'* Amer. Jour. Anat., Vol. 1, No. 3.
^McClure, C. P. W., *06. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialls." Part II, Vol. V, No. 2. (See page 194.)
•Miller, A. M., '03. "The Development of the Post Caval Vein in Birds." Amer. Jour. Anat, Vol. II, No. 3. (See Fig. 5, page 289.)
•Huntington, G. S., and McClure, C. F. W., W. "The Interpretation of the Variations of the Postcava and Tributaries of the Adult Cat, based on their Development." Amer. Jour. Anat, Vol. VI, No. 3, page 33.
This paper was illustrated by reconstructions which have not yet been figured, showing clearly the plexiform nature of the periaortic vessels.
The plexiform arrangement of the postcaval line disappears earlier, both in development and phylogeny, than is the case in the more peripheral regions. Ornithorhynchus alone shows the plexus in any marked degree in the postrenal cava ; in Echidna it has almost disappeared. The determining factor in the formation of these large trunks, by the enlargement of a part of the plexus, we believe lies in the large volume of blood which must pass through the centrally placed vessels. The well-known facts of collateral circulation, following ligation, abundantly prove that a vein responds by growth to an increased flow of blood, that is, its size is determined by its drainage area. Evidently the vessels proximal to the heart have more blood to transmit than any of their tributaries and receive, therefore, a greater stimulus to growth. The hydrodynamic factor operates most intensely at the center, and the development of the venous trunks proceeds from the center toward the periphery by the enlargement of capillaries and plexuses along favorable lines and the resolution of the remaining reticulum into small tributaries. The considerable range in the variation of the post-cava appears due to the approximate parallelism of the channels about the aorta. When vessels inosculate at a very acute angle the freedom of the out-flow into the common trunk must be very nearly equal for both. When both have a common drainage area, as these vessels, it must be a very nice balance that determines which of them is to survive. In many cases it is some external factor, such as the pressure of a muscle, or the development of some organ, e. g., the mesonephros, or the migration of the kidney in the case of the postcardinal, which gives decision when the internal factors seem so nearly in equilibrium. The hydrodynamic lines once established, the plexus resolves itself into tributaries of small size, as in the case of the pelvic vessels.
It remains to determine, if possible, the origin and direction of the major hydrodynamic lines. The earliest vessels in the vertebrate appear as a capillary network which increases at the periphery by the formation of new capillaries in the growing region, while the central areas are constantly being resolved into larger vessels. Beautiful demonstrations of this reticulum have recently been given by Clark^^ and Evans. ^^ The development of the vessels in the chick's blastoderm is too well known to require description, especially in the light of Thoma^s^^ extensive work, but it illustrates admirably a number of points which we desire to emphasize; first, the capillary reticulum ; second, the formation of veins outward from the center^ and third, the presence of a continuous channel at the periphery — the vena terminalis. The drainage lines at first radiate from the center like the spokes of a wheel — ^that is, they correspond to the direction of the growth of the area vasculosa. Later a reduction in their number occurs and larger branching vessels are formed. This seems to be merely a case of the recession of the angle of confluence and the expression of the already cited tendency of V-shaped confluences to develop a Y formation. A very similar phenomenon occurs in the development of the middle cerebral in man. Mall's figures*' show the same changes from reticulum to reticulum with hypertrophy of its radial lines, corresponding to the radial growth or expansion of the pallium, and finally the emei^ence of the brandied veins. The pelvic vessels show the same series of types. It would appear that the primitive hydrodynamic lines conform to the direction of growth. A further illustration is afforded by the early veins of the longitudinally growing body. Lewis* has shown that the first veins in the rabbit are the umbilical and the piecardinal, both of them longitudinal.
Clark, E. R., '09. "Observations on the Living Growing Lymphatics in the Tail of the Frog Larva." Anatomical Record, Vol. Ill, No. 4.
"Evans, H. M., '09. "On the Earliest Blood-vessels in the Anterior Limb Buds of Birds and their Relation to the Primary Subclavian Artery." Amer. Jour. Anat., Vol. IX, No. 2.
We regret that the Important article of Thoma came Into our hands too . late to receive the attention It deserves In the body of our paper. In many places our observations overlap and our conclusions are closely similar. We would point out, however, that the material used Is largely different Thoma working on the chick's area vasculosa was able to demonstrate the emergence of vessels along hydrodynamic lines, proceeding centrlfugally by the enlargement of some of the capillary channels and the reduction of others. That he appreciated the general application of this important observation is shown by the following excerpt: "Auch die doppelten Begleltvenen der Arterlen des Menschen und die Entwlckelung des Venenplexus weisen auf solche Besonder heiten bin, doch wftre m offenbar yerfrtibt, diese Formeigentbiimlicbkelten, bei denen slcher nocb andere Umst&nde mitwlrken, bier ansftibrlicber zu erortem."
"Thoma, R., '©3. "Untersuchungen ttber die Hlstogenese und Hlstomechanik des Gefasssystems." 1893, Stuttgart.
"Mall, F. P., *04. "On the Development of the Blood-vessels of the Brain In the Human Embryo" Amer. Jour. Anat., Vol. IV, No. 1.
"Lewis, F. T., '02. "The Development of the Vena Cava Inferior." Amer. Jour. Anat, Vol. I, No. 3.
Tbls principle we baye sougbt to apply to otber areas. In tbe continuation of bis paper be is interested mainly in tbe arterial system, wbile we baye sougbt to apply certain simple mecbanical views to tbe major Tenons lines. As regards tbe bydrodynamic factors tbemselves, wbile admitting freely tbe Importance of Tboma's findings and tbe ingeniousness of bis deductions, we bave ventured to depart somewbat from bis conclusions notably tbe first of bis bydrodynamic laws^ Witb tbe otber two our paper, from its limited scope, is not concerned. Tbis law is formulated by Tboma as follows : '*Das Wacbstum der Gef&sslicbtung, d. b. das Fl&cbenwacbstbum der Grefftsswand is abbftngig von der Stromgescbwindigkeit des Blutes." It must be borne in mind tbat tbe conditions under wbicb tbe arteries and veins develop are different as are tbe functions wbicb tbey perform, and tbat, tberefore, conclusions arrived at by tbe study of one system cannot be directly transferred to tbe otber, as, for example, tbat in general tbe velocity of fiow determines tbe size of tbe lumen; wbile tbis may bold true for tbe arterial system in itself, it is invalid in a comparison of artery and vein, e. g., compare tbe lumen of tbe aorta witb tbat of tbe postcava. Tbis rule would lead us to expect a larger lumen in tbe aorta tban in tbe cava ; the exact opposite is tbe case. And yet tbese vessels must transmit in one cardiac revokition tbe same volume of blood, unless congestion or anemia of tbeir commoa «rs%. is to result. We are inclined to consider the volume tbe determining factor. Now tbe volume is tbe product of tbe pressure and cross section, tbe smaller tube will deliver in a unit of time the same volume as tbe larger under sufficiently increased pressure. Accordingly we find vessels adapted in two directions to supply tbe volume determined by metabolism of tbe tissues ; first, under conditions of higher pressure, with thicker walls and smaller lumina ; second, under conditions of lower pressure with thinner walls and greater lumina. Tbe velocity of flow, we bold, to be conditioned by these moments, as in the adult by tbe difference between tbe a tergo and the a fronte factors.
In the chick of 36 hours (Fig. 11) is found an arrangement of^ veins closely parallel to the condition existing in the area vasculosa. A centrifugal formation of veins along the hydrodynamic lines which correspond to the direction of growth of the drainage area, and terminates peripherally in a reticulum, bounded by marginal vessels, the umbilical and postcardinal veins, which in this respect resemble the vena terminalis. Proceeding from the periphery to the center, that is, caudo-cephalad, we find first an abundant capillary reticulum, then an area where the retictilum has a somewhat ladderlike figure, the emerging cardinal and umbilical forming the uprights, while the intervening reticulum assumes a transverse disposition. The longitudinal vessels respond by increasing growth to increasing function; their diameter is determined by the length of the area drained, that of the transverse vessels by its widtli, both in rough proportion to the volume of blood they carry and this in turn to their respective drainage areas. Finally we reach distinct areas with lateral tributaries, trunks having emerged along hydrodynamic lines by the solution of a plexus. The formation of a divide between the lines of the umbilical and postcardinal veins is really a simple example of the principle we tried to show as operative in the case of veins convergent at an angle. The marginal arrangement of this drainage system has been alluded to. At first the umbilicals predominate, later they largely lose their function as veins of the somatoplcure and the postcardinals usurp their territory, and becoming united by a reticulum across the aorta form important elements in the periaortic plexus. Here is an obscure instance of the substitution of axial for marginal drainage. Owing to the relatively large volume of blood seeking return along these lines — from the trunk and posterior extremities through the cardinal, and from the allantois through the umbilical — the longitudinal are so accelerated in growth and so dominate the picture that their relation to the reticulum is masked. The phenomenon of deep axial drainage replacing a superficial marginal type which is earlier in time, appears also in the limbs, in the substitution of the axillary and femoral lines for the primitive Rand-venen, while in the tail the lateral caudal veins may possibly be a persistence of the marginal type. Their apparent connection with remnants of the umbilical line in marsupials lends color to this view. The general problem appears worthy of further investigation, especially with reference to the underlying mechanical factors.
Fig. 11. Chick of the thirty-sixth hour. From a reconstruction in the study collection of the Department of Anatomy, Columbia University. Showing the character and disposition of the capillary reticulum between the umbilical and post-cardinal veins.
We have made but little reference to external factors modifying the development of the venous system, both because they have in general received more attention than conditions of flow which it was our purpose to estimate, and because we believe them to be modifying factors only, acting upon otherwise determined hydrodynamic lines. We believe that the retention of multiple points of debouchment by a trunk vein^ of which the venous island or fenestra is a special case, must be explained in this way. It is a survival of a retrogressing plexus, but its retention increases the surface friction of the system. The mechanical factors we have instanced in the reduction of the plexus operate against its persistence, for in the case of a fenestra in a venous trunk, either the recession of the angle of confluence would tend to the fusion and absorption of the walls separating the arms of the loop, or else the arm that fell most nearly into the lines of the eflFerent and aflFerent vessels would have the freer in-let and out-let and so f eceive a greater stimulus to growth. An exact equilibrium, requiring that both arms should converge and diverge at the same angle to the parent trunk, or that one side of the loop should be favored by the entrant, the other by the emergent vessel in equal degree, could not be expected often to occur. One arm would increase, the other decrease, until the favored arm was lost in the continuity of the trunk, the other forming a minute tributary or two, or altogether retrogressing. Evidently an external factor must be sought in the motion of adjacent structures, favoring or impeding flow, now in one arm of the loop, now in the other. Obviously tiie passage of an artery or a nerve through a fenestra does not occasion the persistence of both of its arms. In the case of a muscle, the matter is different ; for example, in Omithorhynchus, the anastomosis lateral to the psoas minor affords escape for the blood when the psoas presses upon the dorsal plexus.
Our argument has, hitherto, been that veins develop out of a capillary reticulum under the influence of hydrodynamic factors. The genesis of the reticulum does not affect its reaction to these factors, yet if the argument which we have presented has validity, its eventual extension to the origin of the capillaries themselves out of inter-cellular spaces may not prove entirely mistaken. Such spaces serving as circulatory channels are described in a number of invertebrates.^* The flow through these spaces might be conceived to occasion a flattening of the surfaces impinging upon the blood stream — the inception of an endothelium, which would thus cease to be an entity and become merely a position modification of the mesenchyme. Its instability as a tissue-form after the ligation of a vessel is well known. The fact that the endothelium of the embryo spreads from the center to the periphery does not preclude the possibility that its characters are determined by its relation to the blood stream, for the flow is most rapid and voluminous at the center and consequently there should be sought its earliest and greatest effects. There also^ the mesenchyme giving rise to the muscularis and adventitia receives its greatest stimulus. We have ventured upon the debatable and very controversial ground of the vascular endothelium, in order to point out that the vital problem of the veins concerns not the great vessela but the capillaries.
"IDahlgren and Kepner. "A Text-book of the Principles of Animal Hlstolq^y." (See Figs. 134, page 151.)
Received for publication August 1, 1909.
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Terry RJ. An observation on the development of the mammalian vomer. (1909) Anat. Rec. 3: 525-.

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This historic 1909 paper by Terry described development of the mammalian vomer. The bone separating the left and right nasal cavities in humans and most vertebrates.



Modern Notes: skull | bone | respiratory


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An Observation on the Development of the Mammalian Vomer

By

Robert J. Terry. From the Department of Comparative Anatomy, Harvard Medical School,

With Two Fiqures.


The name "vomer," given to the unpaired plowshare-shaped bone of the human cranium, has been applied in the works on comparative anatomy to a pair of bones in the skulls of the Sauropsida and Ichthyopsida. This homology, maintained by the earlier writers and by most osteologists up to the present time, is founded largely on the relations of parts in the adult skull. The unpaired vomer of the mammals was explained by assuming it to be the equivalent of a pair fused together, a theory supported by observations on the origin and development of the single vomer in certain teleosts and birds and in man. According to Gaupp^ true paired Anlagen of the vomer have not, however, been seen in the lower mammals.

In 1884 Sutton^ proposed a new homology for the mammalian vomer by claiming its presence in the lower- animals in the parasphenoid, an unpaired bone in the base of the cranium which exists in all classes from the fishes on, except the mammals. The parts in the mammalian cranium which, according to the theory, should correspond with the ichthyopsidan paired vomers, were found in the palatine processes of the premaxillaries. These processes have been observed by Albrecht, Sutton and others to arise independently of, and subsequently to fuse with, the tooth-bearing portions of the prejnaxillaries.


^Gaupp, E. Die Entwickelung des Kopfskelettes. Hertwig's Handbuch der Entwickelungslehre der Wirbeltiere. 1906, Bd. Ill, Zweiter Teil, p. 850.

•Sutton, J. B. Observations on the Parasphenoid, the Vomer and the Palato-pterygoid Arcade. Proc. Zool. Soc, 1884, p. 566.


In later years, Broom^ has contributed much to our knowledge of the comparative anatomy of the vomer, and with evidence adduced from the investigations of Turner, W. K. Parker, Wilson and Symington, he strongly supports the homology of the mammalian vomer and parasphenoid. As to the comparison of the paired vomers of the lower forms w4th the palatine processes of the premaxillaries, he does not agree entirely w^ith Sutton. Broom has suggested the term '^prevomer'^ for the category of bones represented by the paired vomers (of other authors) in the lizard, and finds its homologues in the paired vomers of the Ichthyopsida. But in the great majority of the higher mammals the prevomer does not exist, its place being taken by invasion of the palatine processes of the premaxillaries. These are regarded as true portions of the premaxillaries and not independent elements w^hich Sutton considered them to be. In the dumbbell-shaped bone of Ornithorhynchus and in a median ossification in the nasal region of Miniopterus, Broom identifies the prevomer. These bones, although azygos in the adult, are both derived from a fusion of a pair of splints underlying the cartilages of the vomeronasal organs.

An objection to the comparison of the mammalian vomer and the non-mammalian parasphenoid lies in the fact that the latter presents in the series of animals a history of retrogression ; in the lowest forms the parasphenoid reaches forward to the ethmoidal region, w^hereas in most reptile? and birds its anterior end is far back and away from this region. A more serious obstacle to the new homology is the circumstance, already mentioned, of the single vomer developing from a pair of centers. The one instance in mammals might wvll be taken to be an exception to the rule of single origin, if single origin were known to be the rule. But how many studies have been made by modem methods to determine this matter ?

"Broom, R. On the Iloinology of the Palatine Process of the Mammalian PremaxUlary. Proc. Linn. Soe. N. S. W., 1895. Vol. X, p. 477-485.

On the Occurrence of an Apparently Distlnet I'revomer In Gomphognathus. Jour. Anat. and Physiol., 1896, Vol. XXXI.

On the Mammalian and Reptilian Vomerine Bones. Proc. Linn. Soe. N. S. W., 1902, Vol. XXVII, part 4, p. 545-,')G0.


During the reconstruction of the cranium of a cat embryo there was observed a tendency to bilateral formation of the vomer, and my attention was thereby directed to the question of the origin of this bone in the mammals. A review of the series in the Harvard Embryological Collection resulted in finding one instance of paired origin of the vomer, and tliat in a marsupial. The discovery by Fuchs* of the remains of the parasphenoid in a Didclphys embryo and its bearing on the homology of the mammalian vomer, induced me at this time to communicate the observation. Through the courtesy of Professor ilinot I have been enabled recently to review the sections of the heads of three pouch-specimens of Caluromys (Didelphys) philander in which the paired origin of the vomer had been noted.


Figs. 1 and 2. — Transverse sections tbroiigh the nasal region of a 17 mm. specimen of Caluromys philander; 1, through the anterior ends of the vomers ; 2, through the middle of the vomers. Harvard Emb. Coll., Series 707, Sections 245 and 228. X 39 diam.

A, cartilaginous nasal septum; B, palate; C, vomer; Z>, palate process of premaxilla ; £7, vomeronasal organ of Jacobson.

Fuchs, Hugo. Ueber einen Rest des Parasphenoids bei einem rezenten Saugetiere. Anat. Anz., 1908, Bd. 32, p. 584-590.


In a specimen 18 mm. in length there is present a pair of vomers. These elongate ossifications lie approximately parallel with the ventral edge of the cartilaginous nasal septum and extend from its caudal end forward as far as the middle of the vomero-nasal cartilages of Jacobson. Here the septum is continuous ventrally with the palate, and in this region the vomers are connected with one another across the median line. The connection is a feeble one, consisting of a few delicate bony trabeculse which are present in only three of the section.^. Beyond this place in the caudal direction, the septum and palate are separated by a space, so that the nasal cavities are in communication with each other from side to side. In this region the two vomers are seen to diverge as they are followed backward. Each bone for the most part is compressed, with sharp edges and surfaces directed more or less obliquely — ventrally toward its anterior end, ventrolaterally in the middle of its extent. Anterior to the vomers lie the paired palatine processes of the premaxillaries, adapted to the convex surfaces of the vomero-nasal cartilages. A parasphenoid ossification center was not observed.

The conditions here described were found to be essentially the same in the two other specimens examined which were from the same pouch.

The study of younger specimens may decide whether or not the bony bridges are secondary connections between a pair of independent vomerine ossifications. The large size and advanced state of ossification of the lateral parts is indicative of an earlier origin for them than for the insignificant median ossification. The osteogenetic tissue in which the vomers are developing is disposed in two lateral masses of niesenchyma, connected here and there by strands of the same tissue stretching across the middle line ventrad of the nasal septum. In sections passing through its anterior end, the vomerine ossification tract is found to be unpaired and to be situated beneath the nasal septum, from the perichondrium of which it is well separated. This median mass of osteogenetic tissue is, however, of small extent in comparison with the lateral masses of the tissue, and, except anteriorly, presents itself in strands and not as a continuous bed of mesenchyma.


Relics of the pair of plates which fuse to form the vomer in man are to be found in the ake, projecting conspicuously at the caudal end of the bone. This suggests the probability of the alse of the cat's vomer and of the vomers of other mammals having an origin from paired parts of the developing bone. The dumbbell-shaped bone of Ornitliorhynchus is bifid caudally, a condition which seems to follow from the original paired state of this element. It is not, however, my intention at this time to enter into the question of the phylogeny of the vomer. The object of this communication is to record the paired origin of the vomer in a low mammal, in which class generally it must be insisted that further study of the development is necessary before the bone can be regarded as azygos in its beginning.

Received for publication August 9, 1909.


D ALMOST COMPLETE SUPPRESSION OF THE CUNEIFORM BONES OF A FOOT. AN INSTANCE OF VITAL READJUSTMENT

BY

THOMAS DWIGHT. Parkman Professor of Anatomy, Harvard Medical School.

With Two Figubes.

The following observation is reported not only because it is perhaps unique, but because it is a very striking instance of what might be called vital readjustment

The foot is that of a white man aged 78, and apparently had not attracted any particular notice either before or during dissection. By an unfortunate mischance, the other foot has been lost sight of. The hands showed nothing remarkable beyond disease of one joint of a thumb. The foot consists — apart from the phalanges, which are free and apparently healthy — of the following pieces : the astragalus ; the OS calcis ; the scaphoid, to which the bases of the first and second metatarsals are fused; the cuboid, with which are fused the third and fourth metatarsals and the distal dorsal portion of the external cuneiform; the fifth metatarsal. There is no trace of an internal cuneiform. The external cuneiform is represented by a small part of the dorsal aspect fused with the third metatarsal. It is very doubtful whether the middle cuneiform is represented at all, but it is possible that a small prominence in the sole may represent its distal end. This part of the tarsus is very pathological. The line of the joint between the astragalus and the scaphoid on the dorsal aspect is obscured by irregular bony growths, more or le^s interlocking, which probably interfered with motion, though the joint has persisted. The distal borders of the scaphoid cannot be made out accurately. This bone may be said to be amalgamated with the bases of the first and second metatarsals. Not only is there no sign of an internal or middle cuneiform bone on the dorsum, but the distance from the astragalus to the bases of the metatarsals seems if

(530)


D Suppression of the Cuneiform Bones. 531

anything smaller (certainly no greater) than that usually occupied by the scaphoid. On the inner aspect there is a great prolongation of the scaphoid into an uncommonly sharp tuberosity, which appears on the plantar aspect. The line of the joint with the first metatarsal may be followed in a general way, and there is no hint of any remnant of a cuneiform. A rounded ridge in the sole of the foot, from the base of the second metatarsal to the scaphoid, suggests vaguely a small part of a cuneiform, but nothing can be identified certainly.


The culx)id is distinctly shorter than a normal one, and is inextricably mixed with the bases of the third and fourth metatarsals. The reason for accepting a remnant of the external cuneiform bone is furnished by the position of the joint between these bony mas^ses and the scaphoid. This joint, seen from the dorsum, is proximal to the apparent level of the second metatarsal, which would not be the case were the third metatarsal the only element. The joint of the fifth metatarsal shows some pathological changes, especially on


D 532 Thomas Dwight.

the dorsal aspect. It is much more oblique than is normal, and the tuberosity projects laUrally to an uncommon degree. Accurate measurements of any of the metatarsals, with the exception of the fifth, are out of the question ; but it is quite certain that this one is the longest of all. I believe that Pfitzner never obser^^ed this when making his studies of the relative lengths of the metatarsals. The illustrations show that the normal outlines of the foot have been remarkably well preserved, although the outer side of the foot is longer than it should be, and the tarsus forms too small a part of the whole. The most striking defect in the proportions is the great breadth of the foot. This is not caused by any error of articulation, for the nature of the pieces is such as to admit of practically no choice. The length of the articulated foot, measured from the back of the os calcis to the tip of the second toe, is a little over 21 cm., which is certainly small for a male foot. The greatest trans verse breadth, at the proximal end of the phalanges, is a little more than 9 cm., which is abnormally large. It is a case of very advanced "flat foot." The illustrations make further description unnecessary.

An interesting question is — what caused this condition? That the foot is pathological is very clear ; but nothing is more certain than that extraordinary anomalies are associated with pathology in a way that does not allow us to determine what is cause and what is effect. It does not srem possible that this condition is the consequence of a resection in early life. All we can say is that probably the internal and middle cuneiform bones, as well as the greater part of tiie external one, failed to develop; and that the organism, adapting itself to uncommon circumstances, attempted to preserve the general outline of the foot. The underdevelopment of the cuboid, and the obliquity of the joint between it and the fifth metatarsal are elements in this process.

All one has to do to appreciate how successful the effort at reparation has Ix^en is to put together the bones of a foot, leaving out the inner and middle cuneiforms and the greater part of the external one, and to compare the curves made by lines connecting the heads of the metatarsals or of the terminal phalanges with similar lines drawn on these illustrations. The rnore one thinks of it, the more


D Suppression of the Cuneiform Bones. 533

remarkable does it appear that so good a foot should have been formed under the circumstances. Through what agency has this been brought about ? It seems to me that it is a clear instance of the act of the vital principle regulating growth, and repair; the same by which the amputated leg of a newt is reproduced. I incline to agree with Driesch that it should not be called a vital energy, for it is rather something regulating the energy. He would call it entelechy; a something "which bears the end in itself."^ I find no fault with this, but prefer the other term.

Received for publication July 9, 1909.


The Science and Philosophy of the Organism. By Hans Drlescli, Ph.D. Gifford lectures, 1907-08, Vol. T, p. 144.


D A COMPARATIVE STUDY OF THE LYMPHATICO VENOUS COMMUNICATIONS IN ADULT

MAMMALS.

I. Primates, Cabnivora, Rodentia, Uxgulata and Marsupialia.


BY


CHARLES F. W. McCLURE AND, CHARLES F. SILVESTER. From the Laboratory of Comparative Anatomy, Princeton University.

With Three Text-Figures and Ten Plates.

Huntington and McClure^ have shown in the adult eat {Felis domestica) that the communication between the lymphatic system and the systemic veins may normally occur on each side of the body, within either one of two or within two typical districts. These two districts include, approximately, the angle of confluence formed by the union of the external and internal jugular veins (common jugular angle) and the angle of confluence formed by the union of the external jugular^ and subclavian veins (jugulo-subclavian angle). An examination of a large number of adult cats proved conclusively that neither one of these two districts predominates as the place of communication between the lymphatics and the veins, but that either

IIuntiDgton and McClure, The Anatomy and Development of tlie Jugular Lymph Sacs In the Domestic Cat (Fells domestica). A paper read before The Association of American Anatomists in Chicago, in 1907, published in The Anatomical Record, Volume II, 1908, and soon to be published in a more complete form in The American Journal of Anatomy.

"This vein, strictly speaking, is a common jugular vein in the cat, but on account of its large size, as compared with the internal jugular, is usually spoken of as the external jugular vein of which the internal jugular Is a tributary.

(534)


D Lymphatico- Venous Communications. 535

one of the two or both may serve equally in this capacity and for this reason both districts must be regarded as constituting normal points of communication between the lymphatics and the veins.

In following the development of the jugular lymph sacs in the embryonic cat Huntington and McClure were able to establish the basis upon which the duplex character of the lymphatico-venous communication in the adult rests. They found that the right as


Internal J


Lymph Sao


JagaUur .

Juguur V


SubolATian Thyrootnri

Lympluuio SuboUTian ,


Innomuate V

Text-fig. I. — A reconstruction of the left jugular lymph sac of a 11 mm. cat embryo (Felig domestica) showing the relations of the thyrocervical artery to the jugular and subclavian approaches through which the two typical adult communications are established between the lymphatics and the veins. Ventral view. Drawn from a reconstruction made by Huntington and McClure after the method of Born.

well as the left jugular lymph sac in the embryonic cat invariably presents two caudally directed processes or prolongations which they termed, respectively, the Jugular and Subclavian approaches (Textfig. I). These two processes, on each side of the body, are directed


D 536 Charles F. W. McClure and Charles F. Silvester.

toward and approach the district of the common jugular angle and the district of the jugulo-subclavian angle, respectively, and they observed that it is through either one of the two or through both of these processes that the adult communication is established, a circumstance which accounts not only for the presence of a double communication in the adult cat but also establishes it as a character of morphological significance.

In view of the uniform conditions which prevail in the adult domestic cat concerning the presence of two typical districts of lymphatico-venous communication on each side of the body, the present writers have undertaken to determine to what extent this same uniformity may prevail in adult mammals in general.

We have thus far examined twenty-five (25) species distributed among fifty (50) adult mammals (24 primates, 4 carnivora, 12 rodents, 5 ungulates and 5 marsupials). These mammals Avere chosen at random from the Princeton Collection so that the conditions observed in them represent fairly well the average conditions which one might expect to find in any other similar group chosen in the same manner. The lymphatic system of each mammal was injected with gelatine and then carefully dissected out in the appropriate regions on each side of the body. A drawing to scale was made of each dissection to facilitate comparison. All of the figures in this paper therefore represent accurately the arrangement of the lymphatics as met with in the regions of communication and it is worthy of notice that the lymphatics present a marked variability, more so than the veins, not only in the different species examined but among different members of the same species. These variations will not be dealt with to any extent in the present paper except in so far as it becomes necessary to speak of them in connection with the communications which exist between the lymphatics and the veins.

We may state at the beginning that we are warranted in drawing the conclusion from the adult mammals thus far examined that the lymphatic system normally communicates with the veins in these forms as in the adult cat, either at one of two or at two typical districts (common jugular and jugulo-subclavian districts) and that a commimication at the two typical districts is the commonest of theIC


D D Lymphatico- Venous Communications.


537


three possibilities which may normally occur on either side of the body. This is clearly .shown in the following table (Table I) in which it is seen that a communication between the lymphatics and the veins occurred at the two typical districts on the right side of the body in sixty-two (62) per cent and on the left side in seventyfour (74) per cent of the mammals examined; also, when a communication was present, on either side, at only one of the two typical districts, it occurred more frequently at the common jugular than at the jugulo-subclavian district.

TABLE I,

Showing the Relative Frequency with which the Lymphatico- venous ck>mmunicati0n8 occub on each side of the body at ettheb one of the two ob at both of the typical distbicts of communication in the Fifty Mammals undeb Consideration.


Communication at Common Jugular District only. . .


Communication at JuguloSubclavian District only. .


Right Side.


Left Side.


2 ' .2

t ! g

5 « 


1 3


2;


Communication at both

Districts ;14' 3 8' 2 4 31 ! 62 17 ' 4


— —


c


a> &»


t ? I •= . ft

S , "O ) ^ I «  t ' O C I t


li


1 116 32 I 7 01 3 2


,12 ' 24


3 6' O' 1 Oi 0' 1 , 2

I I 1


81 3 5


37 74


Text-fig. II is a diagram of the precaval system of veins showing the two typical districts of lymphatico-venous communication, encircled by rings, which are met with on each side of the body. Since we have found that the general plan of the communication is fimdamentally the same on each side of the body, in that it normally occurs at either one of the two or at both of the typical districts of communication (Table I), our interest has been largely centered upon the determination of the combinations in which the communications may occur in the fifty mammals examined when both sides of the


D 538


Charles F. W. McClure and Charles F. Silvester.


body are taken into consideration. Since a communication may be normally established in one of three ways on each side of the body, it is evident, when both sides of the body are considered, that the lymphatico-venous communications may occur in nine possible combinations and that each combination may be regarded as a type of


Zai«rB«l Jncater V.




«— @i


Text-fio. II. A diagram of tlie precaval system of veins showing the two typical districts of lymphatico-veiious communication on each side of the body and the nine possible combinations in which communications may occur when both aides of the body are taken into consideration. Ventral view.

communication which characterizes the lymphatico-venous communication of a particular individual.

Each of the nine possible combinations is indicated in Text-fig. II by a series of arrows which radiate from a small circle enclosing the Roman numeral (I-IX) applied to the combination and is also


D Lymphatico- Venous Communications.


539


TABLE II.

Showino the Nine Possible Combinations (Types of Lymphatico- venous Communication) in which Lymphatico-venous Communications may be Normally Established in an Individual when Both Sides of the Body abe taken into Consideration.


Right Side


Left Side


TvnA Common Jugular Jugulo-Sub- I Common Jugular Jugulo-Sub^' District clavlan District, i District. I clavlan District.


I.


TAP


II.


TAP


III. ,


TAP


1 IV. j



V. ■


TAP


VI.


TAP


VII. 1



VIII.



IX.


TAP


TAP


TAP TAP

TAP TAP TAP


TAP TAP TAP TAP TAP

TAP


TAP

TAP TAP

TAP

TAP TAP


Tlie word TAP, under the district designated, indicates the presence of a communication at this district between the lymphatics and the veins.


TABLE III.

Showing the Distribution among the Fifty Mammals Examined of the Nine Possible Combinations or Types of Lymphatico-venous Communication which may be Normally Established in an Individual.


Type.


Total


Primates.


Carnivora 3


Rodentla.


12


8


5



2


3


1



2





2








1





1







24


4



12



Marsu

1 Number and Percentage


nilata.


pialia.

4


of Ind


ivid per


uals.


2


29 or 58


cent.


2



1 9 or 18




1


1


6 or 12







2 or 4







2 or 4







1 1 or 2







1 1 or 2







'










5


'


' 50




D 540 Charles F. W. McClure and Charles F. Silvester.

shown in Table II, in which the word tap indicates the presence of a communication under the district of communication designated.

The following figures illustrate examples of the diflFerent types of lymphatico- venous communication as met with among the fifty mammals examined :

Type I, Figs. 6, PI. Ill (Papio porcarius), 16, PL VI (Putorius vison), 22, PL VII (Cavia porcellus), 26, PL VIII (Sus scrofa domestica) an'd 31, PL X (Didelphys virginiana) .

Type II, Figs. 12, PL V (Anthropopithecus troglodytes) y 21, PL VII {Lepus cuniculus) and 27, PL IX {Sus scrofa domestica).

Type III, Figs. 5, PL II {Papio anubis), 15, PL VI (Canis familians) and 30, PL IX (Didelphys virginiana).

Type IV, Figs. 4, PL II (Papio anubis) and 1, PL I {Nycticebus tardigradus) .

Type V, Figs. 13, PL V {Anthropopithecus troglodytes)^ and 8, PL III (Macacus rhesus).

Type VI, Fig. 19, PL VII (Lepus cuniculus).

Type VII, Fig. 20, PL VII (Lepus cuniculus).

As shown in Table III the lymphatico-venous communication of every mammal examined fell within one of these nine combinations (Types I-IX). This circumstance, together with the fact that in twenty-nine (29) individuals or fifty-eight (58) per cent of those examined (Table III) the communication occurred on both sides of the body at the two typical districts of communication, and that this type of communication was commonly met with in each of the five orders of mammals examined (Type I, see Text-fig. II and Table III), indicates that the embryonic basis for the establishment of two typical communications on each side of the body must be fundamentally and potentially the same in the fifty mammals examined by us as that described by Huntington and McClure for the domestic cat. Although our present deductions do not lead us beyond a consideration of the conditions observed in the fifty mammals (25 species) it is evident, if this conception of two primary and

■It is significant to note in the two chimpanzees examined, in which the precaval system of veins resembles that in man, that Types II and V are represented.


D Lymphatico- Venous Communications. 541

typical districts of communication on each side of the body can be generalized for mammals as a whole, that a consistent description of the adult lymphatico-venous communications should rest upon a morphological interpretation of their development, and not upon the ill-defined and variable conditions which are at present described in works of anatomy as constituting the points at which the lymphatics communicate with the veins.

It is interesting to note that Type VIII, in which a communication occurs on both sides of the body only at the jugulo-subclavian district (angle of confluence formed by the union of the external jugular and subclavian veins), a region commonly assigned by anatomists as the point at which the thoracic and right lymphatic ducts tap the veins, vxis not met with in a single one of the mammals examined.

As shown in Table I and Table III, when a communication is present on each side of the body at only one of the two typical districts it is usually found at the common jugular (Type II) and not at the jugulo-subclavian district.

The assignment of the jugulo-subclavian angle as the point at which in general the lymphatics communicate with the veins in the adult, appears to us to be a correct interpretation for the cat and for the mammals we have thus far examined, only in the sense that the two districts of confluence formed by the union of the external and internal jugular and by the union of the external jugular and subclavian veins, respectively, be regarded as constituting a single district of communication.

Tables IV to VIII, inclusive, show in tabulated form the different species of mammals examined by us as well as the type of lymphatico-venous communication presented by each individual.'*

The word tap in each column, under the district designated, indicates the presence of a communication at this district between the lymphatics and the veins, while the absence of the word tap indicates that a communication is wanting.

The number after the sex sign of each species indicates the cata

The nomenclature of the species mentioned in this paper follows that given in Trouessart's Catalogus Mammalium, Quinquennale Supplement. 1904.


D 642


Charles F. W. McClure and Charles F. Silvester.


TABLE IV.— PRIMATES.


Nyciicebus tardigradus

9 2374 (Fig. l.PLI.).... Callithrix jacchus

9 2457

Cebus capucinus

9 2481 (Fig.2, PL I.)... Cehu8 hypoleucus

9 2472

Ateles hybridua

^^2433

Ateles hybridua

c?2435

Ateles vellerosua

9 2476 (Fig. 3, PI. I.)... Papio anubis

9 2368 (Fig. 4, PI. II.).. Papio anubis

c^ 2432 (Fig. 5, PI. II.) . . Papio porcarius

d' 2453 (Fig. 6, PI. III.) . Papio porcarius

d2\m

Macacus speciosus

d 2376 (Fig. 7, PI. III.) . Ma>cacu8 irhestis

9 2487 (Fig. 8, PL III.) . Afacacus wmestrinus

d'2458(Fig. 9, PI. IV.).. Alacaciis nemestrinus

9 2459

Macacus nemestrinus

d* 2461

Macacus nemestrinus

d 2483

Cercocfbus fuliginosus

9 2394

Cercopithecu^ callUrichus

d 2434

Cercopithocus cMlitrich u s

d 2464 (Fig. 10, PI. IV.). Cercopithecus cnllitrichus

9 2477(Fig. 11,P1. V.).. Cercopithecus cnllitrichus

d 2478

Anthropopithrnis troglodytes

d2467(Fig. 12, Pl.V.).. A nthropopithpcus troglodytes

9 2468(Fie. 13, Pl.V.)..


Right Side.


Type.


Common Jugular District.


IV



I


TAP


I


TAP


I


TAP


II


TAP


III


TAP


I


TAP


IV



III


TAP


I


TAP


I


TAP


II


TAP


V


TAP


II


TAP


I


TAP


III


TAP


I


TAP


II


TAP


I


TAP


I


TAP


I


TAP


I


TAP


II


TAP


V


TAP


Jugulo Subclavian

District.


TAP TAP TAP TAP


TAP TAP

TAP TAP

TAP

TAP

TAP

TAP TAP TAP

TAP

TAP


Left Side.


Common Jugular IHstrict.


TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP TAP


Jugalo Subclavian

District.


TAP TAP TAP TAP

TAP TAP TAP TAP TAP TAP


TAP TAP TAP

TAP TAP TAP TAP


D Lymphatico- Venous Communications.


543


TABLE v.— CARNIVORA.



Type.


Right Side.


Left Side.



Common Jugular DiBtriot.

TAP TAP TAP TAP


Jugulo Subclavian

District.


Common 1 Jugular 1 District.

TAP TAP

TAP

1

TAP


Jugulo Subclavian

District.


Felis domestica

d'2452(Fig. 14,P1.V.).. Canis familiaris

$2451 (Fig. 15, PI. VI.). Putorius vison

6^2384 (Fig. 16, PL VI.). Mephitis putida

6^2362 (Fig. 17, PL VI.).


I III

I I


TAP 1

TAP TAP


TAP TAP TAP TAP


TABLE VI.— RODENTIA.


Right Side.


Lepus cunictUus

(^2363 (Fig. 18, PL VII.)., Lepus cuniculus

(5^2364 (Fig. 19, PL VII.). Lepus cuniculus

d^2366 (Fig. 20, PL VII.). Lepus cuniculus

6^2367

Lepus cuniculus

$2431 (Fig, 21, PL VIL). Cavia porcellus

(^2359

Cavia porcellus

6^2360 (Fig 22, PL VII.). Fiber ziheihicus

d*2361

Fiber ziheihicus

(^2365 (Fig. 23, PL VIII.). Fiber zibethicus

$2395

Marmota monax

$2469 (Fig. 24, PL VIII.). Seiurus hudsonius

$2466 (Fig. 25, PL VIII.).


Type. ,


Common Jugular District.


TAP TAP

TAP

TAP

TAP

TAP

TAP

TAP

TAP

TAP !

TAP !


Jugulo Subclavian

District.


TAP

TAP TAP

TAP TAP

TAP TAP TAP TAP


Left Side.


Common Jugular District.


Jugulo Subclavian

District.


TAP


1

TAP



TAP


TAP



TAP


TAP


TAP



TAP


TAP


TAP


TAP


TAP



TAP


TAP


TAP


TAP


TAP


TAP


TAP


TAP


D 544 Charles F. W. McClure and Charles F. Silvester.

TABLE VII.— UNGULATA.


! Type.


Su8 scrofa domestica

9 2436 (Fig. 26, PI. VIII.). Sus scrofa domestica

9 2437 (Fig. 27, PI. IX.) . Sti8 scrofa domestica

92438

Sus scrofa domestica

6^2439

Stis scrofa domestica

9 2441 (Fig. 28, PI. IX.)..


I I

I "

I III

I II

1 I


Richt Side.


Common Jugidar District.


TAP TAP TAP TAP TAP


Juinilo Subolavi&n

District.


Left Side.


TAP


TAP


Common Jugular District.


TAP TAP TAP TAP TAP


Juffulo Subclavian

IMstrict.


TAP


TAP


TAP


TABLE VIII.— MARSUPIALIA.



Type


Riffht Side.


j Left Side.



Common Jugular District.


Jugulo Subclavian

District.


Common 1 Jugular 1 District.


Jugulo Subeiavian

District.


Didelphys virginiana

d^2388(Fig. 29,P1.IX.)... Didelphys virginiana

^91


TAP TAP


TAP TAP

TAP TAP


TAP

TAP

TAP

! TAP

TAP

1


TAP TAP


Didelphys virginiana

9 96 (Fig. 30, PI. IX.).... Didelphys virginiana

990


III TAP I TAP

I 1 TAP


TAP TAP


Did4phys virginiana

d^5r(Fig 31,P1.X.)


TAP


logue number of the individual in the Princeton Collection. The individuals figured in this paper are also designated in these tables.

Before proct^eding to a detailed description of the lymphaticovcnous communications observed in the fifty mammals, we will first consider the general character of the two typical districts of lymphatico-venous communication.

Text-fig. Ill is a composite diagram of the prccaval system of veins constructed on the basis of the conditions actually observed in the fiftv mammals under consideration and should be constantly referred to in connection wath the following description of the external and internal jugular and cephalic veins.


D Lymphatico- Venous Communications.


545


1. The External and Internal Jugular Veins.

The external jugular may be larger (Fig. 16, PI. VI) or smaller (Fig. 12, PI. V) than the internal jugular vein, or, of practically the same size (Fig. 5, PI. II).

The common jugular district of lymphatico-venous communication may lie on the same level and in close proximity to the jugulo-sub


RIOHT

Exteraa.1 Jugular V


Internal Jugular V


LEFT External Jugular V


Cephalio V.


Ciavielo



Ccpbalio V.


"Clavicle


Text-fig. III. — A composite diagram of the precaval system of veins constructed on the basis of the conditions observed in the fifty mammals examined and with especial reference to the relations of the two typical districts of lymphatico-venous communication to each other. Ventral view.

clavian district as in Papio porcarius (Fig. 6, PI. Ill) or, as is usually the case in the domestic cat, it may lie somewhat cranial to the jugulo-subclavian district as shown on the right side of Fig. 14 (PI. V) and on the right side of Text-fig. III. In either case, however, the two districts of communication are separated from each other by the external jugular vein.

In the domestic cat the internal jugular vein at times gives up


D 540 Charles F. W. McClure and Charles F. Silvester.

its original connection with the external jugular and then drains into the innominate through the inferior thyroid vein. In a case obser\'ed by us in which this occurred (Fig. 14, PI. V, left side), the common jugular district of lyraphatico-venous communication was not transferred to the new angle of confluence formed by the union of the inferior thyroid and innominate veins but remained on the external jugular at the point where, as on the right side of the same individual (Fig. 14, P1..V, right side), the internal jugular normally joins the external jugular vein.

2. The External Jugular and Cephalic Veins.

As is well known, the cephalic vein presents considerable variability in its relations to the external jugular and subclavian veins, not only in mammals in general but even upon opposite sides of the same individual. The complex of vessels connected with the external jugular and subclavian veins on both sides of Text-fig. III. represents a composite picture of the conditions observed in the fifty mammals examined by us and is an attempt to explain, from the standpoint of comparative anatomy, the variable conditions of the cephalic vein, as well as those sometimes presented by the external jugular, the transverse scapular and deep transverse scapular veins. One might infer from a study of comparative anatomy that this complex of veins may possibly represent a ground-plan arrangement and that the elements of which it is composed are capable of serving in variable capacities, not only in different individuals, but even upon opposite sides of the same individual.

In explanation of the basis upon which the above observations are made the following description of the conditions actually met with, to be compared with the diagram (Text-fig. Ill), is given.

One of the commonest terminations of the cephalic vein met with is its connection with the external jugular, as in Felis dome^tica (Fig. 14, PI. V), Cams familiaris (Fig. 15, PI. VI), Putorius vison (Fig. 16, PI. VI), Fiber zihethicus (Fig. 23, PI. VIII), Cat>ia parceUus (Fig. 22, PI. VII), and Sits scrofa dom^stica (Fig. 26, PI. VIII), where it is commonly established through the vessel C or D in Text-fig. III. It may be formed, as in Maca^us rhesus (Fig. 8,


D Lymphatico- Venous Communications. 547

PL III), Cercopithecus callitrichus (Fig. 11, PI. V) and Cebus capucinus (Fig. 2, PI. I), through the retention of the vessels B and D in Text-fig. Ill, as is also the case in Didelphys virginiana (Fig. 31, PI. X, left side). It may also be formed in Didelphys virginiana (Fig. 31, PL X, right side), as is more commonly the case,^ through the retention of the vessels A and D in Text-fig. III. In Sciurus hudsoniiLs (Fig. 25, PL VIII) it may be formed through the retention of the vessel C in Text-fig. Ill, but vessels B and D may also be present where they, together with the external jugular vein, form a loop or ring through which the clavicle passes. In one specimen of Ateles vellerosus examined (Fig. 3, PL I), in which there is an asynmietrical arrangement of the veins on opposite sides, the cephalic vein is formed through the retention of the vessel A in Text-fig. Ill on the right side and by the vessel B on the left. Although the conditions observed in Ateles are probably abnormal, they sen-e as a good general illustration of the variability manifested by termination of the cephalic vein.

The elements which compose the complex of veins ordinarily entering into the formation of the cephalic also appear to be capable of functioning as the terminals of veins other than the cephalic. For example, in Lepus cunicuhis (Fig. 20, PL VII) the transverse scapular vein appears to have been established through the vessel B in Text-fig. Ill which in Ateles vellerosus (Fig. 3, PL I, left side) and in part in Macacus rhesus (Fig. 8, PL III) constitutes the terminal of the cephalic vein. Also in Marmota monax (Fig. 24, PL VIII), as shown by its relation to the clavicle, the external jugular vein has largely transferred its drainage from its conventional pathway to the vessel B in Text-fig. Ill which now functions as the chief terminal of the external jugular vein.

At first sight one might regard the boundaries of the two typical districts of lymphatico-venous communication as being fundamentally modified in accordance with the variations presented by the veins in the region of the lymphatico-venous communications. Such does

•^C. F. W. McClure, A Contribution to the Anatomy and Development of the Venous System in Didelphys marsuplalis. Part I, Anatomy. Amer. Jour, of Anatomy, Vol. II, 1903 (see Fig. II, p. 377).


D 548 (^harles F. W. McClure and Charles F.. Silvester.

not appear to be the case, however, since the primary relations established by the union of the external and internal jugulars and by the external jugular and subclavian veins, respectively, definitely mark out the two typical districts of communication as evidenced by the constancy with which communications occur in connection with these districts, regardless of the variation presented by the veins.

We pass now to a consideration of the general character of the lymphatico-venous communications as met with in the fifty mammals examined.

When a communication occurred on either side, at either one of the two typical districts, it was usually single in character as shown in Table IX. In only a few instances were the lymphatics found to communicate with the veins within either of the two typical districts by more than one opening. A multiple communication between the lymphatics and the veins was found at the common jugular district of communication in Ateles vellerosus (Fig. 3, PI. I, right side), in Cercopithecus callitrichus (Fig. 11, PI. V, both sides), in Felis domestica {Y\g. 14, PI. V, right side), in Macacus nemestriuus (Fig. 9, PL IV, both sides) and the the jugulo-subclavian district of communication in Cards familiaris (Fig. 15, PI. VI, left side) and in C ercopiihecus callitrichus (Fig. 10, PI. IV, right side).

As shown in the following table, only twelve (12) instances of a multiple communication at the two typical districts were met with and it occurred more frequently on the right than on the left side of the body.

One hundred and seventy-eight (178) points of communication between the lymphatics and the veins were observed by us on both sides of the body in the fifty mammals under consideration (89 on each side). Of these, one hundred and forty-two (142) were found either at the angles of confluence formed by the union of the external and internal jugular and by the union of the external jugular and subclavian veins, respectively, or w-ere included within these two angles, as illustrated by Figs. 12, PI. V, 13, PL V {Anthropopithecus troglodytes), 8, PL I (Ateles vellerosus), 7, PL III


D Lymphatico- Venous Communications.


549


{Macacus speciosus), 8, . PI. Ill (Macacus rhesus), 1, PI. I {Nyticehus tardigradus) y 4, PL II, 5, PL II (Papio anubis), 22, PL VII (Cavia porcellus), 19, PL VII, 20, PL VII, 21, PL VII (Lepus cuniculus), 24, PL VIII (Marmota monax), 25, PL VIII {Sciums hudsonius) and 27, PL IX (Sus scrofa domestica).


TABLE IX. Showing the Pbedominance of a Single over a Multh^le Communication

AT each of the two TYPICAL DlSTMCfTS OF LyMPHATICO-VENOUS COMMUNICATION.


Right Side.


Left Side.


Single Communication at Common Jugular District 19


Multiple Communication at Common Jugular District


Communication Wanting at Common Jugular District


Total.


11! 3 5

[ I 2


4 12 1 5; 5


I I


! I


o I 6


41 22 4 11

6i' 2!

3|. ij^ 60 ' 24 4 I 12


5i 6 47 2


5 6


1 50


Single Communication at Jugulo- 1

Subclavian District 13 ' 3 9 2,4

I , I

Multiple Communication at Jugulo-' ! i


tipU

UDCl


Subclavian District 3


i 1


Communication Wanting at Jugulo- I

Subclavian District ISil 3 31


Total.


I 24 4 I 12 . 6 5


17


1 3 9

1


3


5


37 1


7


3


2



12


24


4 12


i 5 5


50


Three (3) points of communication met with did not fall either within the angle of confluence formed by the union of the external and internal jugular nor within the angle formed by the union of the external jugular and subclavian veins, but, as in Figs. 2, PI. I {Cehus capucinus, right side), 28, PI". IX (Sus scrofa domestica.


D 550 Charles F. W. :McClure and Charles F. Silvester.

left side) and 14, PL V {Felts domestica, right side), they occurred on the veins slightly caudal to the angle of venous confluence (caudal to the common jugular angle in Cebus and Felis, and to the jugulosubclavian angle in Sus).

Also, in addition to these three points of conununication just mentioned, thirty-three (33) others were met with which did not fall within the common jugular nor jugulo-subclavian angles but which were dorsally or ventrally situated on the veins in dose proximity to either one of the two of these angles.

Of these dorsal and ventral communications between the lymphatics and the veins, the former proved to be the more common of the two.

A dorsal conmiunication between the lymphatics and the veins on both sides of the body at the conmion jugular district of communication is shown in Figs. 15, PI. VI {Cards familiaris) and 17, PL VI (Mephitis putida). A dorsal communication between the lymphatics and the veins on the right side of the body at the common jugular district of communication is shown in Figs. 10, PL IV {Cercopithecus callitrichus) and 9, PL IV {Macacus nemestrinus) and at the jugulo-subclavian district of conmaunication in Fig. 23. PL VIII (Fiber zibethicus). A dorsal communication between the lymphatics and the veins on the left side of the body at the jugulosubclavian district of communication is shown in Figs. 29, PL IX (Didelphys virginiana) and 26, PL VIII (Sus scrofa domeslica).

A ventral communication between the lymphatics and the veins on both sides of the body at the common jugular district of communication is shown in Figs. 11, PL V (Cercopithecus callitrichus) and at the jugulo-subclavian district in Fig. 17, PL VI (Mephitis putida). A ventral communication between the lymphatics and the veins on the left side of the body at the jugulo-subclavian district of communication is shown in Fig. 6, PL III (Papio porcarius) and on the right side of the body in Fig. 11, PL V (Cercopithecus cailitrichus) .

In consideration of the large number of commimications observed within the common jugular and jugulo-subclavian angles (142), the presence of these thirty-six apparently variant forms appears to


D Lymphatico- Venous Communications. 551

find its explanation in the circumstances that the communications established between the embryonic jugular lymph sac and the veins are not confined exclusively within these two angles of venous confluence but may vary about the same in a sphere which we have designated a district of communication (Text-figs. II and III). The circumstance that angle, dorsal, and ventral communications may be found in the same individual, in which they hold definite relations to either one of the two typical angles of venous confluence and that, in some cases, dorsal and ventral communications are alone present (Fig. 17, PI. VI), seems conclusive evidence that all of the points of communication observed by us between the lymphatics and the veins must have been established in the embryo in fundamentally the same manner as in the domestic cat and in definite relation to two typical districts of commimication.

Received for pubUcation July 9, 1909.


D EXPLANATION OF PLATES I TO X.

Figs. 1 to 31, inclusive, were drawn to scale from dissections of adult mammals and represent ventral views of the veins and lymphatic vessels in the regions where the lymphatics communicate with the veins.

The veins are draAvn in outline, the lymphatics are colored. The word TAP indicates a point at which the lymphatics communicate v^th the systemic veins.

The name of the species represented is given under each figure while a complete list of the mammals dissected and studied in connection with this paper may be found in Tables TV, V, VI, VTI and VIII.


D D D D LYMPH ATICO-VENOUS COMMUNICATIONS. CHAHLES F. W. MCCLURB AND CHARLES F. SILVESTER.


BiaaT


Int«maL Jugular V


i


Cepbaj



SuboUTian v


^


AiygM V.



Fio. 1 (Type IV)

Slow Loris ?

yifcticchus tanlipradus, Linn.


TOMICAL RECORD. VOL. Ill, NO. 10.


D PLATE I.


BIQBT External Jugular V


Internal Jugular V


Ceptaalio V


LEFT External Jugular V



Fig. 2 (Type I)

Capuchin Monkey $

Cchus capucinus, Linn.


AIQflT External Jugular V


Cei


Internal Jugular V


/


LEFT External Jugular V



8u


\


Thoraoio Duot


SubolaTian V


'Bronchomediastinal Trunk


Fig. 3 (Type I) Spider Monkey $ Ateles vellerosus, Gray


D D D LYMPH ATICO-VENOUS COM MUNICATIONS. CHARLES F. W. MCCLURE AND CHARLES F. SILVESTER.


Fic. 4 (Type IV)

Aiiubis Baboon 5

Papio anuhis F. Cuv.


The Anatomical Record. — Vol. III. No. 10.

D BIOflT External Jogalar V


Internal Jus^ilar V


LEFT


qplUfcUO V.


»nl


Aaygos V


Thoraoio Dnot.



Thoracic Duct.


Fig. 5 (Type III)

Auubis Baboon (^

Papio antihis, F. Cuv.


D D D LYMPH ATICO-VENOUS COM M UNICATI0N8. CHARLKS F. W. MCOLl'RE AND CHARLES F. SILVESTER.



Fig. 6 (Type I)

Chacama Baboon J

Papio porcarius, Bodd.


/

TfaoTMsie Doc


Fig. I

JapaiM


Thb Axatomical Record. — Vol. Ill, No. 10.


D PLATE III.


Internal Jugnlar V


aiOHT External Jagular V.


LEFT External Jugular V.


Thoracic Duct.


II)

C?

«, Cuv.


Fig. 8 (Type V)

Rhesus Monkey J

Macacus rhesus, Audebert


Cephalic V



D D D D D LYMPHATICO-VENOUS COMMUNICATIONS. CHARLES F. W. MCCLCRE AND CHARLES F. SILVESTER.


Fig. 4 (Type IV)

Anubis Baboon 5

Papio anubis F. Ciiv.


Tub Anatomical Uecord. — Vol. III. No. 10.

D PLATE II.


RIOflT Bztenud JogaUu* V


Internal Jugular V


\ _


LBFT External Jugular V


BobolaTiaa 1


Thoraoio Dnot.



Tboraoio Duot


Fig. 5 (Type III)

Auubis Babo(3ii ^

Papio anuhis, F. Cuv.


D D D LYMPIIATICO-VENOUS COM U UNICATIONS. CHARLES F. W. MCCLURB AND CHARLES F. SILVESTER.


BIQflT Bztanial Jagalar V


Inumal JusuUr V


Cephalic V.



Fig. 6 (Type I)

Chacairia Baboon J

Papio porcariHs, Bodd,


/

Thoracic Dtt(


Tub Anatomical Record. — Vol. Ill, No. 10.


Fig. 7

JapaD<

Miicacus « 


D PLATE III.


Internal Jugular V


EIGHT External Jugular V.


LEFT External Jugular V.


Thoracic Duct.


II) K«, CuV.


Fig. 8 (Type V)

Rhesus Monkey J

Macacus rhesus, Audebert


Cepbalio T



)igitized by IC


D D LY MPHATICO- VENOUS COM M l X ICATIONS. CHARLES F. W. MCCLURE AND CHARLES P. SILVESTER.


BIOfiT Bxtemal Jugulftr V


IsEFT MxtantalJngalmr V



Fig. 9 (Type II)

PIg-talled Macaque c?

Macacus nemestrinuSy Linn.


The Anatomical Record. — Vol. Ill, No. 10.


D PLATE IV.


Internal Jugular V


BIGHT External Jugular V


LEFT ternal JuguJar T



Subclavian V.


- Thoracic Duel.


Aaygot V.


Fig. 10 (Type I)

Green Monkey J

Cercopithecua callitrichus, Geoflf.


D D D D D LYMPH ATICO-VENOU8 COMMUNICATIONS. CHARLES F. W. MCCLURE AND CHARLES P. SILVESTER.


Exeernol JnguUr V.


Cephalic



P y Extcnial Jogalmr r


SnbcUnaa T.


Seoff.


Internal Jugular V.


RIGHT External Jugular V,


LEFT External Jugnlar V.



Thoracic Duoi.

Fig. 13 (Type V)

Chiiupanzee $

Anthropopithecus troglcHfytes, Linn.


Tham


Aiith


J


"IIB ANATOMICAL RECORD. VOL. Ill, NO. 10.


D Internal Jugular V.

/


LEFT Sztemal JugnUr V.



Subclavian V.


ymph Nodes


VIK


Aorta

(Type II) panzee d iS troglodytes, Linn.


)igitized by IC


D D LYMPHATIC0-VEN0U8 COMMUNICATIONS. C'HABLES F. W. MCCLURE AND CHARLES P. SILVESTER.


aiOBT Sxtonul Jugular V



lAtMiial JagnlAr V.



olftvian V.


o IHiet.


A*JCM V.


-— Aorte


Fig. 16 (Type I)

Mink c?

Putorius vison, Brlsson


'I'HK ANATOMICAL RECORD. VOL. Ill, NO. 10.


D PLATE VI.


RIGHT


B3tt4


LEFT Extornal Jugular V.



Subclavian V.


Thoracic Duct.


'. 15 (Type III)

Dog $ f familiarise Linn.


LEFT


F

Meph


D LYMPHATICO-VENOUS COM M UNICATIONS. CHARLES F. W. MCCLUKK AND CHABLES P. SILVESTER.


BIOBT External Jugular V


LEFT External Jngalar V


Internal Jugular V.



Trans. Sea


Subolan


Internal Jugular V.


BIGHT Ti-ana. Soap. V.



I ^4^ PrMsava


Thoraoio Duct.


Fig. 18 (Type I) Rabbit c? Lcpus cuniculus, Linn. TOMicAL Record,— Vol. Ill, No. 10.


r

alar V


Internal


V uiceniBi


Fig. 19 (Type VI)

Rabbit d

Lepus cwiiculus, Linn.


Subola Thor*


▲sygoa


D Aortaj

Fig. 20 i

Lcpus rutm


PLATE VII.


LEFT


Scapul


BFT rogular \


Fig. 21 (Type II) cephaUo v Rabbit $

^'•^^ .Trana. Scap. V.^^PW* CUniCUlUS, Linil.


Subclavian V.


Precava



LEFT External Jugular V


Cephalic V


h


Lymph Hodes


VII) > Linn.



Subclavian V.


Subclavian V


Thoracic Duot


▲orta

Fig. 22 (Type I)

Guiiiea-Pig ^

Cavia porccUus, Linn.


D D D D D LYMt»MATlCO-VENOUS COM M UNICATHJNS. riiAULRR P. W. MCCLl'RK AND CHARLKS P. SILVESTER.


BIGHT Eztornal Jugular V.


Cepbalio V.


SIGHT External Jngalar V.


Intornal Jugular V


Captaalio V.


Cepbalio V



Fig. 24 (Typk I)

Ground Ilog $

Marmota momix, Llnii


LEFT External Jugular V


Fig. 23 (Type I)

Musk' Rat c?

Fiber zibethUvH, Linn.


Thoraoic Duot


Asygoa V


'TOMicAL Record. — Vol. Ill, No. 10.


D PLATE Vin.


SxternalJ


LETT sternal Jugular V.


Uo V.


Oapha


Subol


BIGHT Sztomal Jugular V


h


LEFl Szternal Jn


Internal Jugular V


A


Cepbalio V.


phaiiov. Fig. 26 (Type I)

Pig 2 S!u8 scrofd domcstica. Gray


Subolaviai


Fig. 25 (Type i) Red Squirrel $ iurus hudsonius, Erxleb.


r


uwrcMJAU J^UO(.


D D D D D LYMPHATICO-VKNOrs COM M INICATIONS.

CHAULKS F. W. McrhritK AM) rilAHLKS F. SILVKSTER.


I.EFT

Internal JagnUr V External JaculAr V


Bnbolai .^

V.


Fig.

rig ?

Su8 8(rofa domes tica. Gray


LBPT BIGHT External Jugular V


Sufc


nidi The Anatomical Kkcord — Vol. 111. No. 10.

D RIGHT Internal Jugular V


J)i<Jeli)hifS rirgiiiiaiia. Km*


Plate IX.


D D I» M ATICO-VEN0U8 COM M UNICATIONS.

ftl^KH F. W, MCCLL'RE AND CHARLKS F. SILVESTER.


Plate X.


BIGiiT BxMnud JofiiUr V


LEFT Bxt«rn«l JoguUr V


liTiole


GUvicl


Sub


Fig. 31 (Type I)

Opossum (J

Didelphys virginiana, Kerr


The anatomical Record. — Vol. Ill, No. 10.


D D D D NOTES.

Doctor Irving Hardesty has been appointed Professor of Anatomy in Tulane University. The department, which formerly included only gross anatomy, will now have charge of histology as well. Professor Hardesty will be assisted by Assistant Professor Henry W. Stiles, M.D., formerly of the University of Michigan ; Assistant Professor Henry Bayou, A.M., M.D., and Mr. H. H. Bullard, A.B., M.S., formerly of the University of Missouri, who will be Instructor in Anatomy. The following physicians will be assistant demonstrators : Dr. Sidney P. Delaup, B.Sc. ; Dr. Marion S. Souchon ; Dr. John F. Oechsner; while Dr. Charles A. Wallbillich, Dr. John F. Points and Dr. M. H. McGuire will be junior assistant demonstrators. Professor Hardesty, Professor Stiles and Mr. Bullard, as well as the technical assistant, Mr. Linstaedt, will give their entire time to the department. Dr. Edmond Souchon has been made Professor Emeritus of Anatomy and Curator of the Museum.

Eichard E. Scammon, A.M. (University of Kansas), has recently been awarded the degree of Doctor of Philosophy by the Faculty of Arts and Sciences of Harvard University, for studies in medical sciences,- particularly in embryology. He is thus the first candidate to avail himself of the new arrangement whereby this degree may be obtained by study and investigation conducted in the Medical School. Dr. Scammon's thesis will be published as the Normentafel zur Entwichlungsgeschichte des Squalus acanthias in Professor KeibePs series.


(553)


D D THE

ANATOMICAL RECORD

Vol. III. NOVEMBER, 1909 No. 11

A NOTE ON THE ORGANIZATION OF THE VENOUS

RETURN WITH ESPECIAL REFERENCE TO

THE ILIAC VEINS.

BY

H. VON W. SCHULTE and FREDERICK TILNEY. From the Anatomical Laboratory of Columbia University,

With EleVek Figures.

This paper is an attempt to formulate a few general propositions having reference to the organization of the venous system as a whole, and further to indicate some of the underlying hydrodynamic factors incident to the formation of the major lines of drainage. Broadly speaking, the veins of the mammal between the peripheral capillaries and the heart fall into two fairly definable regions, a central district of large venous trunks and a distal region of smaller plexiform vessels. The circulation in the adult differs from that of its embryo largely in the reduction of these plexuses to form larger single veins, the zone of plexiform veins retreating farther toward the periphery.

The result of the substitution of large trunks for plexuses is the reduction of the impediment offered to the venous return by surface friction, consequently either a reduction of cardiac work or, the work performed by the heart remaining the same, a more rapid circulation and potentially a higher rate of metabolism.

We conceive that it is the general competency of the circulation as a whole, rather than the topographical situation of the lines of

(555)


D 556 H. von W. Schiilte and Frederick Tilney.

venous drainage, which is of evolutionary significance. Natural \ selection would easily be imagined to operate to destroy an animal whose venous system offered too great a resistance to the flow of the blood, while it is by no means obvious that, given a circulatory competency, the exact topography of a vein can often be of moment to its possessor. The high variability of veins is common knowledge and lends support to this view.

A cursory examination of the variations of the venous system in the three forms most extensively studied, man, the opossum^ and the cat,^ suffices to show that while variations in the situations of the individual veins and even in the topography of the major trunks are wide in range and frequent in occurrence, yet points at which plexus formations replace single veins are subject to relatively little change — ^the anatomic plan varies widely within limits rigidly fixed by physiologic efficiency. It might then fairly be expected that the evolution of the venous system, in its broad outlines, should be in the direction of organization and higher physiological efficiency, rather than the formation of a series of morphologic types. From this standpoint the venous system of the monotremes appears to us a generalized type of low organization, comparable to the embryonic veins of marsupials and placentals.

In Omithorhynchus the plexiform arrangement involves even the postcavflB to the renal level (Figs. 1 and 2). The two vessels are connected dors'ally by massive anastomoses. Traced caudad to about the lumbo-sacral junction each postcava resolves itself into two extensive plexuses, one dorsal and the other ventro-mesial to the psoas minor. At the lateral border of the muscle a wide channel connects the two plexuses ; the dorsal plexus is composed of tributaries, enumerated cephalo-caudad as follows:

1. An ilio-lumbar plexus.

McClure, C. F. W., *03. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialis." Part I. Amer. Jour. Anat, Vol. II, No. 3.

•Darrach, W., '07. "Variations in the Postcava and its tributaries as observed in 605 Examples of the Domestic Cat." Amer. Jour. Anat., Vol. VI, No. 3, page 30.



I


Organization of the Venous Eetum. 557


. ANASTOMOSIS ILIO-LUMBAfl PI iAL PLEXUS

•APHENA P

A FOR PSOAS iPSMORAL PLI APHENOUS PLEXUS


CAUDAL PLEXUS

Fig. 1. Ornithorbynchus paradoxus. From a dissection in the study collection of the Department of Anatomy, Columbia University. Showing the postcavfe and their tributaries Ventral view, semi-diagrammatic. The aorta and branches have been omitted to allow the dorsal anastomoses between the postcavfie to come into view. The psoas minor of the left side Is also omitted.


D Fig. 2. Ornithorhynchus paradoxus. Dorsal view. From a dissection in tlie study collection of tlie Department of Anatomy, Columbia University. After injection the vessels were removed in mass.


D Organization of the Venous Return. 559

2. A large trunk from the dorsum of the thigh (saphena parva).

3. Veins coming from the fat pad of the groin.

4. A femoral plexus.

It is noteworthy that the drainage from the panniculus and the subpannicular fat of the trunk is accomplished by large veins (vide supra 2 and 3), while that from the deeper parts is given by the plexiform vessels accompanying the arteries. The ventro-mesial plexus is composed from without inward of the following plexiform vessels :

1. A deep epigastric which receives a considerable plexus from

the thigh.

2. An internal iliac, receiving the obturator and vesico-pudendal

plexuses.

3. A caudal plexus.

Across the median line the plexuses of the two sides anastomose freely dorsad of the aorta, and ventrally more or less completely across its large branches.

It is, of course, arguable that the circulatory system of Omithorhynchus is not primitive, but highly specialized in adaptation to the animal's semi-aquatic habits. Besembling, as it does, the venous plexuses of the cetacea, though it differs in degree and constitution, no one would deny that it stands in relation to the creature's habits. But it by no means follows that it is highly specialized, since a retention of the embryonic characters in the adult may have as high adaptive value as the development of new characters. In the extensive plexus formation, the thin walls of the vessels and the excess in lumen of the veins over the arteries, we have a picture closely resembling the vessels of the embryos of higher forms, — a system of vessels in which a relatively small column of blood reaches the capillaries through the small and often plexiform arteries, accumulates in the veins and sluggishly returns to the heart. This condition is undoubtedly one of low physiological organization, fitted by the multiplicity of its venous paths to serve as a composite schema of the variants of the venous system in higher mammals. Further in Echidna, which is not an aquatic animal, but little reduction of the plexus has


D 560 H. von W. Schulte and Frederick Tilney.

occurred. It is significant that this reduction affects the postaortic anastomoses.

In turning from the monotreme to the marsupial, we find in the latter an immense advance in the organization of the venous return. Not only the postcava but also the iliac and often the caudal vein are free of plexus formation, though there is not infrequently a remnant of the plexus in the form of "venous islands" in the region of the promontory, yet even these are fewer than in such placental forms as the edentate or even the cat, and they are far less extensive than in cetacea.

If the plexuses of monotremes are primitive, as we take them to be, it becomes a problem to deduce from them the trunk drainage of the marsupials and placentals. A few details of the morphol(^y of the marsupial veins are a necessary preliminary.

In a specimen of Trichosurus (Fig. 3) the cava is formed by the confluence of a number of radially disposed vessels, the ilio-lumbar, external iliac and internal- iliac veins. The left internal iliac receives the caudal. The specimen shows, perhaps, a slight tendency to the formation of a common internal iliac trunk. Compared to this tbe monotreme presents a great excess of vessels in its fan-shaped plexuses, while here we have, as it were, only the ribs of the fan, the intervening web reduced to small tributaries of the major trunks. Kadial hydrodynamic lines have developed and there has followed, as must follow, a reduction of the network. It is obvious that if two converging veins of equal size are connected by a homogeneous reticulum, the blood flows from all parts of the reticulum under the vis-a-tergo of the arteries and the suction through the veins of the cardiac diastole (Fig. 4). It follows that the blood will flow from the center of the reticulum toward the large veins, and that the periphery will have not only to transmit the blood directly reaching its meshes but also to drain the central areas. Its function, therefore, is at a maximum near the large veins, and diminished toward the center where, as it were, a watershed is formed, dividing the reticulum into two drainage areas. The peripheral parts of the plexus persist as small tributaries of the veins favored by the hydrodynamic lines (Fig. 5), and resolve themselves into smaller vessels and capillaries



I


Organization of the Venous Return. 5G1


ILIOLUMBAR VEINS


i EXT. LATERALIS


ILIACA EXT. MEDIALfS


CAUDAL VEIN


FiQ. 3. Trichosurus vulpecula. From a dissection in the study collection of the Department of Anatomy, Columbia University. Postcava and pelvic veins showing radial arrangement


D Fig. 4.


Fig. 5.


D Organization of the Venous Return. 563

as the divide is approached. Our knowledge of the ontogeny of the pelvic vessels in marsupials is unfortunately small, yet it seems fair to argue from the redundancy of fcetal vessels everywhere, that some such reducing factor as we have mentioned is active mechanically in occasioning the substitution of trunk vessels for plexus formation.

The radial arrangement of the pelvic vessels described above appears to be unstable even in Trichosurus. (Fig. 6.) Besides the specimen of Trichosurus figured, it occurs, so far as we are aware, only in Pseudochirus where it is complicated by the presence of venous rings about the large arteries. Elsewhere the arrangement is disturbed by a tendency of adjacent, ultimately confluent trunks to form a conmion vessel of greater or less extent, transforming the V shape of their union into a Y, and giving rise to an apparent distad recession of the angle of union. The trunks thus affected are the external and internal iliacs with the resultant common iliac — an almost constant formation in the Australian marsupial — or the two internal iliacs to produce a common internal iliac as often in Didelphys virginiana. Trichosurus appears as the starting point of these two types, inclining, however, markedly to form a common iliac In either case the result is the same, the reduction of friction and a displacement of the angle of confluence distad. This phenomenon seems capable of mechanical explanation. Given two equal veins inosculating proximally and connected distally with drainage areas which are increasing in size, an increasing venous return demands an increase in the size of the veins. The trunk proximal of the union tends to lie in the prolongation of the axis of the angle of union (Roux). At this point, therefore, the blood stream changes its direction. Its momentum may be decomposed by the parallelogram of forces into a moment acting in the axis of the resulting vessel and a moment at right angles to this, tending to push the walls of the tributaries into closer approximation and to form a spur at the angle of confluence (Fig. 8). Thus more and more the uniting vessels would tend to have their proximal segments parallel, with their walls in apposition. This spur will sustain the pressure of the b'lOod stream upon both sides, which constitutes an abnormal


D 564 H. von W. Schulte and Frederick Tiln^.



Fig. 6. Trichosurus vulpecula. From a dissection in tlie study collection of tlie Department of Anatomy, Columbia University. Showing common iliac type.


D Oi^anization of the Venous Return.


environment for its cells, tending to its ultimate reductionr McMurrich* has reported cases in man of partial persistence of such formations in the iliac veins. Against this mode of accounting for the Y type, an alternative explanation may be argued. It might be held that the recession of the angle was apparent only, that actually a new confluence had been formed by the development of a cross channel through a more distal portion of the reticulum. As will appear subsequently, we are far from denying this possibility, but interpret it as the disturbing result of factors extrinsic to the circulatory system itself, in fact as an example of the establishment of a collateral circulation following interference in a hydrodynamic line (Fig. 9).


Fig. 7.


Fig. 8.


■McMurrich, J. P., *06. "The Occurrence of Congenital Adhesions In the Common Iliac Veins and their Relation to Thrombosis of the Femoral and Iliac Veins." Brit. Med. Jour., II, page 1699.

H. von W. Schulte and Frederick Tilney.


In our figure, should such a factor operate upon the segment B tending to its destruction, flow would be reversed in the reticulum previously draining into it, and a new channel such as C would result from the enlargement of portions of the reticulum responding to the increased function required below the obstacle. But apart from such external interference, the line B would tend to be retained, for the inlet from B' is freer into B which is in line with it, than into the diverging channel C. A good illustration of the displacement of the angle distad is afforded by the vessels in the blastoderm of the chick. The caudal vein in marsupials is subject to a wider range of variation than the iliac vessels. In Phascolomys (Fig. 10) in addition to a mouth in the left common iliac it is connected by three pairs of transverse branches with the internal iliacs^ forming a sort of grill pattern. In one individual of Phascolarctos a closely similar arrangement was found. In both of these forms the tail is rudimentary. In other marsupials it usually opens by a single mouth into one or other common or internal iliac, only occasionally retaining the remnant of a plexus in multiple points* of debouchment. Followed distad it soon breaks up (usually at the root of the tail) into a plexus surrounding the caudal artery. A distinction can thus be drawn between the large-tailed forms and those having short tails, in reference to the caudal vein, which in the latter forms retains more of its plexiform character. Evidently the size of the drainage area, the volume of blood to be transmitted, is the determining' factor in the evolution of trunk veins as against plexuses. The existence of traces of plexus formation in some individuals of the Macropodidse does not militate against this view, as here a large part of the caudal return is provided by subcutaneous channels.



Fig. 9.

In general the larger the area drained — the greater the length of the trunk in the proximal portion of its drainage line — ^the farther distal is the point at which the plexuses occur. A familiar example is the comparison of the V. femoralis and the V. poplitea in man with his Vv. brachiales which are plexiform. The caudal vein is, however, a more convincing example, as here such disturbing factors as might result from the upright position of man may be excluded.

The arrangements of the common and external iliac veins among the marsupials are of considerable theoretic importance. Two types may be distinguished in the relation of the vein and artery. In Didelphys* the external iliac vein lies lateral to the artery. In the Australian marsupial the leg is drained by channels lying mesial to the artery (Figs. 3 and 10), external iliac and common iliac veins. Intermediate forms, however, occur. In Trichosurus and Phascolomys, for example, there is sometimes in addition to the large critally placed vessel a smaller lateral one, varying in development and inosculating distally with the external iliac near the groin, but not at a constant level. It receives tributaries from the psoasiliacus and may show a plexiform character. In the elephant (Darrach) double external iliacs accompany the artery, one lateral, one mesial. The same arrangement occurs in the 20 mm. cat embryo (Huntington). In monotremes a plexus accompanies the arteries. The evidence, while admitted fragmentary, appears to us to warrant the conclusion that the external iliac vein results from the solution of a plexus.


McClure, C. F. W., '03. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialis." Part I, Amer. Jour. Anat., Vol. II, No. 3. (See plates.)


Fig. 10. Phascolomys Mitchell!. From a. dissection in the study collection of the Department of Anatomy, Ck>lumbia University Showing vena iliaca externa lateralis, vena iliaca externa medialis and grill pattern of caudal veins.



While in the case of the internal iliac vein, reduplication of the vessel has not been observed among the marsupials, so far as we are aware, yet the variety in its relation to the artery — it may be dorsal or ventral, lateral or mesial — su^ests a similar origin. And again the monotreme has the plexus.

The corollary follows that these homonymous great veins are not morphological equivalents; the V. iliaca externa lateralis is not morphologically the same as the V. iliaca externa medialis, but results from a specialization of a different area of plexus. The veins are homodynamous, agreeing in function, that is in the drainage of similar areas ; and it thud appears that the anatomical names of veins designate not morphological but physiological units. The hydrodynamic line of drainage is far more constant than the morphological structures which compose it, and unconsciously this drainage line has been the subject of our nomenclature. A more striking illustration is afforded by the term postcava, as already pointed out by Dwight' and Lewis.® This vessel is composed of morphological, distinctly defined elements, sinus venosus, vena hepatica communis, hepatic sinusoids, subcardinal, supracardinal and postcardinal veins. In the marsupial the cardinal collateral replaces the supracardinal in this list. The post-renal element may be cardinal, supracardinal or cardinal collateral ; it may be double or single to the right or left in front of the aorta. Apart from its parallelism to the aorta, its only constant character is that it drains the tail, the hinder extremity and one or both of the gonads according to its site, at one side or in front of the aorta. It is obvious that we are dealing with a definite line and area of drainage, which may be aflFected indifferently well by any one of a series of vessels. The term postcava only indicates this hydrodynamic line. The case here is essentially the same as we have attempted to show for the external iliac. A venous plexus surrounding the aorta is antecedent to the formation of trunk vessels. The variously named cardinals are merely dilated portions of chis reticulum along the major hydrodynamic lines, which, responding to the large volume of blood they transmit, dominate the picture. The smaller transverse channels were long treated as of little morphological importance, except where from external factors in the course of development, the flow became retarded in one of the longitudinal vessels, when they entered the field of consciousness under the term anastomosis as a means of accounting for the emergence or enlargement of another longitudinal line. The early investigators of the development of the venous system rarely figured these plexuses, and their schemata showing only the longitudinal hydrodynamic lines, still illuminate our text-books and adumbrate the subject. Recent workers give more complete figures (Lewis,® ; Miller,® ; Huntington and McClure,®).

•Dwight, Thomas, '01. "What constitutes the Inferior Cava." Anat. Anzelg., Vol. XIX, pages 29-30.

•Lewis, F. T., *02. "The Development of the Vena Cava Inferior.'* Amer. Jour. Anat., Vol. 1, No. 3.

^McClure, C. P. W., *06. "A Contribution to the Anatomy and Development of the Venous System of Didelphys marsupialls." Part II, Vol. V, No. 2. (See page 194.)


•Miller, A. M., '03. "The Development of the Post Caval Vein in Birds." Amer. Jour. Anat, Vol. II, No. 3. (See Fig. 5, page 289.)

•Huntington, G. S., and McClure, C. F. W., W. "The Interpretation of the Variations of the Postcava and Tributaries of the Adult Cat, based on their Development." Amer. Jour. Anat, Vol. VI, No. 3, page 33.

This paper was illustrated by reconstructions which have not yet been figured, showing clearly the plexiform nature of the periaortic vessels.


The plexiform arrangement of the postcaval line disappears earlier, both in development and phylogeny, than is the case in the more peripheral regions. Ornithorhynchus alone shows the plexus in any marked degree in the postrenal cava ; in Echidna it has almost disappeared. The determining factor in the formation of these large trunks, by the enlargement of a part of the plexus, we believe lies in the large volume of blood which must pass through the centrally placed vessels. The well-known facts of collateral circulation, following ligation, abundantly prove that a vein responds by growth to an increased flow of blood, that is, its size is determined by its drainage area. Evidently the vessels proximal to the heart have more blood to transmit than any of their tributaries and receive, therefore, a greater stimulus to growth. The hydrodynamic factor operates most intensely at the center, and the development of the venous trunks proceeds from the center toward the periphery by the enlargement of capillaries and plexuses along favorable lines and the resolution of the remaining reticulum into small tributaries. The considerable range in the variation of the post-cava appears due to the approximate parallelism of the channels about the aorta. When vessels inosculate at a very acute angle the freedom of the out-flow into the common trunk must be very nearly equal for both. When both have a common drainage area, as these vessels, it must be a very nice balance that determines which of them is to survive. In many cases it is some external factor, such as the pressure of a muscle, or the development of some organ, e. g., the mesonephros, or the migration of the kidney in the case of the postcardinal, which gives decision when the internal factors seem so nearly in equilibrium. The hydrodynamic lines once established, the plexus resolves itself into tributaries of small size, as in the case of the pelvic vessels.

It remains to determine, if possible, the origin and direction of the major hydrodynamic lines. The earliest vessels in the vertebrate appear as a capillary network which increases at the periphery by the formation of new capillaries in the growing region, while the central areas are constantly being resolved into larger vessels. Beautiful demonstrations of this reticulum have recently been given by Clark^^ and Evans. ^^ The development of the vessels in the chick's blastoderm is too well known to require description, especially in the light of Thoma^s^^ extensive work, but it illustrates admirably a number of points which we desire to emphasize; first, the capillary reticulum ; second, the formation of veins outward from the center^ and third, the presence of a continuous channel at the periphery — the vena terminalis. The drainage lines at first radiate from the center like the spokes of a wheel — ^that is, they correspond to the direction of the growth of the area vasculosa. Later a reduction in their number occurs and larger branching vessels are formed. This seems to be merely a case of the recession of the angle of confluence and the expression of the already cited tendency of V-shaped confluences to develop a Y formation. A very similar phenomenon occurs in the development of the middle cerebral in man. Mall's figures*' show the same changes from reticulum to reticulum with hypertrophy of its radial lines, corresponding to the radial growth or expansion of the pallium, and finally the emei^ence of the brandied veins. The pelvic vessels show the same series of types. It would appear that the primitive hydrodynamic lines conform to the direction of growth. A further illustration is afforded by the early veins of the longitudinally growing body. Lewis* has shown that the first veins in the rabbit are the umbilical and the piecardinal, both of them longitudinal.

Clark, E. R., '09. "Observations on the Living Growing Lymphatics in the Tail of the Frog Larva." Anatomical Record, Vol. Ill, No. 4.

"Evans, H. M., '09. "On the Earliest Blood-vessels in the Anterior Limb Buds of Birds and their Relation to the Primary Subclavian Artery." Amer. Jour. Anat., Vol. IX, No. 2.


We regret that the Important article of Thoma came Into our hands too . late to receive the attention It deserves In the body of our paper. In many places our observations overlap and our conclusions are closely similar. We would point out, however, that the material used Is largely different Thoma working on the chick's area vasculosa was able to demonstrate the emergence of vessels along hydrodynamic lines, proceeding centrlfugally by the enlargement of some of the capillary channels and the reduction of others. That he appreciated the general application of this important observation is shown by the following excerpt: "Auch die doppelten Begleltvenen der Arterlen des Menschen und die Entwlckelung des Venenplexus weisen auf solche Besonder heiten bin, doch wftre m offenbar yerfrtibt, diese Formeigentbiimlicbkelten, bei denen slcher nocb andere Umst&nde mitwlrken, bier ansftibrlicber zu erortem."


"Thoma, R., '©3. "Untersuchungen ttber die Hlstogenese und Hlstomechanik des Gefasssystems." 1893, Stuttgart.

"Mall, F. P., *04. "On the Development of the Blood-vessels of the Brain In the Human Embryo" Amer. Jour. Anat., Vol. IV, No. 1.

"Lewis, F. T., '02. "The Development of the Vena Cava Inferior." Amer. Jour. Anat, Vol. I, No. 3.


Tbls principle we baye sougbt to apply to otber areas. In tbe continuation of bis paper be is interested mainly in tbe arterial system, wbile we baye sougbt to apply certain simple mecbanical views to tbe major Tenons lines. As regards tbe bydrodynamic factors tbemselves, wbile admitting freely tbe Importance of Tboma's findings and tbe ingeniousness of bis deductions, we bave ventured to depart somewbat from bis conclusions notably tbe first of bis bydrodynamic laws^ Witb tbe otber two our paper, from its limited scope, is not concerned. Tbis law is formulated by Tboma as follows : '*Das Wacbstum der Gef&sslicbtung, d. b. das Fl&cbenwacbstbum der Grefftsswand is abbftngig von der Stromgescbwindigkeit des Blutes." It must be borne in mind tbat tbe conditions under wbicb tbe arteries and veins develop are different as are tbe functions wbicb tbey perform, and tbat, tberefore, conclusions arrived at by tbe study of one system cannot be directly transferred to tbe otber, as, for example, tbat in general tbe velocity of fiow determines tbe size of tbe lumen; wbile tbis may bold true for tbe arterial system in itself, it is invalid in a comparison of artery and vein, e. g., compare tbe lumen of tbe aorta witb tbat of tbe postcava. Tbis rule would lead us to expect a larger lumen in tbe aorta tban in tbe cava ; the exact opposite is tbe case. And yet tbese vessels must transmit in one cardiac revokition tbe same volume of blood, unless congestion or anemia of tbeir commoa «rs%. is to result. We are inclined to consider the volume tbe determining factor. Now tbe volume is tbe product of tbe pressure and cross section, tbe smaller tube will deliver in a unit of time the same volume as tbe larger under sufficiently increased pressure. Accordingly we find vessels adapted in two directions to supply tbe volume determined by metabolism of tbe tissues ; first, under conditions of higher pressure, with thicker walls and smaller lumina ; second, under conditions of lower pressure with thinner walls and greater lumina. Tbe velocity of flow, we bold, to be conditioned by these moments, as in the adult by tbe difference between tbe a tergo and the a fronte factors.


In the chick of 36 hours (Fig. 11) is found an arrangement of^ veins closely parallel to the condition existing in the area vasculosa. A centrifugal formation of veins along the hydrodynamic lines which correspond to the direction of growth of the drainage area, and terminates peripherally in a reticulum, bounded by marginal vessels, the umbilical and postcardinal veins, which in this respect resemble the vena terminalis. Proceeding from the periphery to the center, that is, caudo-cephalad, we find first an abundant capillary reticulum, then an area where the retictilum has a somewhat ladderlike figure, the emerging cardinal and umbilical forming the uprights, while the intervening reticulum assumes a transverse disposition. The longitudinal vessels respond by increasing growth to increasing function; their diameter is determined by the length of the area drained, that of the transverse vessels by its widtli, both in rough proportion to the volume of blood they carry and this in turn to their respective drainage areas. Finally we reach distinct areas with lateral tributaries, trunks having emerged along hydrodynamic lines by the solution of a plexus. The formation of a divide between the lines of the umbilical and postcardinal veins is really a simple example of the principle we tried to show as operative in the case of veins convergent at an angle. The marginal arrangement of this drainage system has been alluded to. At first the umbilicals predominate, later they largely lose their function as veins of the somatoplcure and the postcardinals usurp their territory, and becoming united by a reticulum across the aorta form important elements in the periaortic plexus. Here is an obscure instance of the substitution of axial for marginal drainage. Owing to the relatively large volume of blood seeking return along these lines — from the trunk and posterior extremities through the cardinal, and from the allantois through the umbilical — the longitudinal are so accelerated in growth and so dominate the picture that their relation to the reticulum is masked. The phenomenon of deep axial drainage replacing a superficial marginal type which is earlier in time, appears also in the limbs, in the substitution of the axillary and femoral lines for the primitive Rand-venen, while in the tail the lateral caudal veins may possibly be a persistence of the marginal type. Their apparent connection with remnants of the umbilical line in marsupials lends color to this view. The general problem appears worthy of further investigation, especially with reference to the underlying mechanical factors.



Fig. 11. Chick of the thirty-sixth hour. From a reconstruction in the study collection of the Department of Anatomy, Columbia University. Showing the character and disposition of the capillary reticulum between the umbilical and post-cardinal veins.


We have made but little reference to external factors modifying the development of the venous system, both because they have in general received more attention than conditions of flow which it was our purpose to estimate, and because we believe them to be modifying factors only, acting upon otherwise determined hydrodynamic lines. We believe that the retention of multiple points of debouchment by a trunk vein^ of which the venous island or fenestra is a special case, must be explained in this way. It is a survival of a retrogressing plexus, but its retention increases the surface friction of the system. The mechanical factors we have instanced in the reduction of the plexus operate against its persistence, for in the case of a fenestra in a venous trunk, either the recession of the angle of confluence would tend to the fusion and absorption of the walls separating the arms of the loop, or else the arm that fell most nearly into the lines of the eflFerent and aflFerent vessels would have the freer in-let and out-let and so f eceive a greater stimulus to growth. An exact equilibrium, requiring that both arms should converge and diverge at the same angle to the parent trunk, or that one side of the loop should be favored by the entrant, the other by the emergent vessel in equal degree, could not be expected often to occur. One arm would increase, the other decrease, until the favored arm was lost in the continuity of the trunk, the other forming a minute tributary or two, or altogether retrogressing. Evidently an external factor must be sought in the motion of adjacent structures, favoring or impeding flow, now in one arm of the loop, now in the other. Obviously tiie passage of an artery or a nerve through a fenestra does not occasion the persistence of both of its arms. In the case of a muscle, the matter is different ; for example, in Omithorhynchus, the anastomosis lateral to the psoas minor affords escape for the blood when the psoas presses upon the dorsal plexus.


Our argument has, hitherto, been that veins develop out of a capillary reticulum under the influence of hydrodynamic factors. The genesis of the reticulum does not affect its reaction to these factors, yet if the argument which we have presented has validity, its eventual extension to the origin of the capillaries themselves out of inter-cellular spaces may not prove entirely mistaken. Such spaces serving as circulatory channels are described in a number of invertebrates.^* The flow through these spaces might be conceived to occasion a flattening of the surfaces impinging upon the blood stream — the inception of an endothelium, which would thus cease to be an entity and become merely a position modification of the mesenchyme. Its instability as a tissue-form after the ligation of a vessel is well known. The fact that the endothelium of the embryo spreads from the center to the periphery does not preclude the possibility that its characters are determined by its relation to the blood stream, for the flow is most rapid and voluminous at the center and consequently there should be sought its earliest and greatest effects. There also^ the mesenchyme giving rise to the muscularis and adventitia receives its greatest stimulus. We have ventured upon the debatable and very controversial ground of the vascular endothelium, in order to point out that the vital problem of the veins concerns not the great vessela but the capillaries.

"IDahlgren and Kepner. "A Text-book of the Principles of Animal Hlstolq^y." (See Figs. 134, page 151.)



Received for publication August 1, 1909.

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