Talk:Book - Normal Plates of the Development of Vertebrates 5
88
Normentafeln zur Entwicklungsg«:>chiclile der \VirbelticrL-. N _ _ ormentafel zur Entwicklungsgeschichte des Menschen. 89
eingezeichnet, der Raum zwischen dem er<ten eingezeichneten Ursewment und dem ()hrbI:i<chen ist aher so ' ' ' ‘ ~ ‘ -“ - wir lner amehen, bei allen hinreichend bekannten Formen sind di " " ' e Unterschiede so in die Augen fallend,
«lais ein Blick genugt, um die Differentialdiagnose zu machen. Wir verweisen daffir aufO.HER1'WIGs Handhuch, wo KEIBEL die Entwicklung der aufberen Kérperform der Wirbeltierembryonen ausffihrlich be- arbritet und (lurch zahlreiche Abbildungen erlautert hat. Eine Verwechslung Von menschlichen Embryonen
mit 501C119“ Wm Saumpsideni Wie Sie DOC}! V01‘ 30 Jahren einem Fachmanne zustofien konnte und damals zu einer léingeren Diskussion fiihrte, darf wohl heute als ausgeschlossen gelten.
grofi, dafi fedenfalls noch 5 Ursegmentpaare {fir ihn anzunehmen sind. Das Medullarrnhr des Iimnscliliclien Embryo ist léingt geschlossen, das des Makaken zeigt vorn Reste des vorderen Neuroporus und ist kaudal noch ofien, sogar Reste des Primitivstreifens sind noch vorhanden, wahrend solche bei dem I11€nSC|)1iCllt']1 Embryo langst verschwunden sind. Da braucht man sich nicht gerade dariiber zu wundern, dafii die Aelm. lichkeit zwischen diesen beiden Embryonen keine sehr grofie ist.
Dann hat SELENKA den menschlichen Embryo Lr (No. 0 der Hisschen Normentafel) neben den Makakenembryo Cd gestellt, von dem man Menschenatfen, 5. Lief., Fig. I8, 19 und 20, p. 352, grgfjgere Abbildungen findet. Der menschliche Embryo Lr ist zweifellos anormal. eine Aehnlichkeit zwischen ihm ’ ’ "’ "**~ und dem Makaken Cd kéinnen wir beim besten Willen nicht finden. Auch zwischen dem Gesicht des menschlichen Embryo, das SELENKA in Fig. I7 abbildet, und dem Makakengesicht Fig. 19 ist die Aehn1ich- keit gewifi nicht grofi zu nennen. Sind aber die Stadien gliicklicher gewéihlt, wie speziell bei den von Die Tahellen. HUBRECHT angezogenen Textfigg. 13-I5, so erscheint uns doch die Aehnlichkeit zwischen Affen~ und
Menschenembryonen recht weitgehendl Gewisse Umerschiede sind vorhanden abgesehen mm schwa Dem fiber das Aufstellen der Tabellen in den friiheren Normentafeln Gesagten ist hier nichts Besonderes v nz
vor allem der, dafi infolge der stéirkeren Gehimentwicklung der Kopf des menschlichen Embryo gr6IS hmzuzufugen. er
ist als der der abgebildeten Makaken und Surili. Offenbar héingt damit auch die starkere Entwickl d ling‘ er Nackenbeuge beim Menschen zusammen.
Die in der Normentafel bearbeiteten Embryonen gehéiren den beiden ersten Monaten an. Selbst-
V . , _ verstandlich ist, dais nicht alle Stadien dieser Entwicklungsperiode gleich reichlich vertreten sind. Wahrend, ergleichen Wll‘ mit den SELENKASChen Figg. 13—I5 nun die
von HUBRECHT herangezogenen Figg. 8-11 der Normentafel vcn Tarsius so kiinnen wir ihm keines - we 5 - stimmen. Sehen wir auch ab von der auffallenden Grififle der Augen der Tarsius Embryone ' tgd 2:, _ - n, so IS 0c the gauze Gestaltung des Kopfes der Affenembryonen der des menschlichen iihnlicher. Bedincrt wird djese Abweichung des embryonalen Tarsius-Kopfes von den Kéipfen gleich weit entwickelter M h B d Ag ensc en- un en-
embryonen dadurch, dafi die Hemispharen des Grofihims bei ihnen schwéicher e t ’ k It ‘ d 1 b ‘ n wic e 1 und Menschen, S n a S 61 Affen
worauf wir mehrfach hingewiesen haben, einzelne Liicken zu beklagen sind, héiuft sich an anderen Stellen das Material doch schon so, dafi fast identische Stadien mehrfach vorkommen und es Schwierigkeiten machte, die Reihenfolge der Tabellen festzustellen. Hier wird man schon einen Einblick in die Varationsbreite gewisser Entwicklungsvorgéinge gewinnen ktinnen. Zu bedenken ist freilich, dais, wenn wir auch recht wahlerisch verfahren sind, doch nicht alle Embryonen die Note ,,gut“ ohne weiteres verdienen, das eine oder
dag demgegeniiber aber das Mittelhjm cine ganz besonders Starke Entwickl .gt S andere Pathologische mag immerhin mitunterlaufen, auch lieis sich zwischen den Bearbeitem in Wien, Upsala, ung zei . o
tritt in der Profillinie die Einsenkung zwischen Hemispharenbereich und Mittelh' d’ b ‘ M h irn, 1e elm ensc en und auchbeimfeneb fin‘ b‘ -_ . . . . . . . "3 "Y°“e“ 3“ "5: Elm Tarsms Embryo nicht in die Erscheinung. Mit der germgeren Ge-
samtentwinklung des Geh' ha d - . .
_ F ‘ M ‘"15 ‘:81 am: zusammen, dai3 die Nackenbeuge bei den Tarsms-Embryonen der
m "35 sfimlefl Wélllger ausgebildet ist als bei den Aifenembryonen oder gar bei de d .. * nen es
at-flie Aaahnluc“ bk ‘ '
, elf zwischen den Afl’en- und Menschenembryonen hervorgehoben —-Emhflonen den mensehlichen nicht so nahesteht wie die der ’ y menschlichen und Tarsius-Embryonen
Lund und Freiburg i. B. trotz des guten Willens von allen Seiten eine vollkommene Uebereinstimmung in
der Beurteilung der einzelnen, zum Teil schwierigen Entwicklungsvorgange nicht erreichen; ist es doch fiir -
den Einzelnen, bei einer Arbeit, die sich iiber ein jahrzehnt ausdehnt, und die vielfach unterbrochen werden
mufste, schwer, immer genau den gleichen Standpunkt festzuhalten, besonders wenn es, wie hier vielfach,
nicht mtsglich war, das schon untersuchte Material immer wieder zum Vergleiche heranzuziehen. Das mfige
man bedenken, um unsere Angaben billig zu beurteilen. Diejenigen Tabellen, die den Befund von Embryonen
wiedergeben, welche nach der Art ihrer Gewinnung und nach ihrem Erhaltungszustande ganz besondetes
Vertrauen verdienen, sind von uns mit einem Stern bezeichnet Worden.
' » sind bei beiden weniger stark entwickelt
Notmuncudn nut Entwlellungugunlnehn der W1rbaluun. VIII. 1;
Normentafeln zur Enhviclilllngsgescluvghtx‘ der \Vll'llL'lIIL‘Tf‘.
1 1 _ _‘ _
, 1; 1» _ ~ Prm1iriv- 1 ur- ~ , x v~ » I 1 ‘ ' — —— —-— 1 —
E . an. Alter lxisrperforin streifen ‘scgmemei (_honl.a ‘ r\uge1 Ohr ‘Nasu ,\,],_md Verdauuxig.» Um‘ 1
- :__,_77 1”’ _ V _ _; 1 l tractus1d H’1'11n11us,' genita|- 1Her/. und Geféfie Saint
- 1 Lg" d K _ _ > 1 _ _ _ _ ‘ I 1 1 ’ Z" ‘Z’? L9he1:r‘;::_ 1 [V-I“;t‘;‘é‘Cl‘|"“‘ system 1 g
ge es -€lXnSChllCle.\‘ Fl:'acl'Ierl\e|_n1sch1ld'nnt langemAm\'orderen Keme Chorduin‘ Flm.'l1e Pan _ 3 1 W.’ '_ , ‘ ,_ _ ,, Mensch’. 1.17 mm, Bre|te_ o,_6_mm Pnmmystrelfen. D16 Meclullar- Ends des ‘Urwirbel. das Ento-‘ .\ledul|ar- 4 #7 7 I 1-finge des Pnmmv- , nnne zst angelegt. 1 Primitiv- ‘ Clerm 1 rinne. derK0 ll‘ 1 Gefiil5- und Blur- Emb 0 ‘ f . . . .. . 1 We P . IT _ s rel ens 0,5 mm. Durch-:1 Der Keimschnld llefil dem streirens d1e1 1 einge- 1 1\leduIlar- noch 1 [anlagen aut dem DE Frti'lJS8|.;I;ess{e3I;3:ti;2rslI39ottnersacka: Eroflgn _Dtpttters_afckl ach ilufignlage des sclialtet. wiilste noch 1 Schwanz- 1 1D0‘t5T5"iCk>G9f5l5€‘ gen m , 1 I111 ‘ er nmx ws re: en t’ 1' - ‘ 1 ' _ 1 h .‘ - B h‘t' 1 d des Hem, b) emster 0.9 min. . Ebene des iibri enle clllldecsl ::eIrsi::1E:r1 _ ll]l|()Cll1]ta(E)e(7l-:- 1 I 1 darmbuc t l ‘ll1<:.m;ll;r:nlzeenl¢lI;n‘ Prof. D“|'Chm€SS€l'd€|’EllI0l'IlBI' ,Wulst vor dem analis neur-} (ob durch- ‘ l arenzr ' l l Chorion. 1 KROEN1G- 3) P"“3ue1z“"Obe|f‘fl5ChE ‘entericus, der rechts und links giingi , ist 1' D ' l l Keine Geféffie im1 Freiburg des Utel'lI_Sl|1_mcnS In der’ ‘von ihm kaudalwfirts ausléiuftlfragllcfi) am 1 1‘ ‘ 1Embryonal;:ebilde.l i. Br. Schnittnchtung 1 1 hintereu ‘ ‘ . . 914 mm 1 ' 1 1 1 1 "T b)senkrechtdaz|’13,z mm. 1 AE?de dllje 2 TFi9- I-3 Durchmesser der Ei- 1 l lglgfiliellerl ’ “mg - kapsel in den entspre-l b ' ‘ chenden Richtungen i H-l-em ran‘ 13 mm und 5 mm. I‘Pa:;:1em'3fs ‘ Linge der Chorionzotten I stfeifens 1 ! o,5—i,9 mm. 05 mm
- 3 Die Anhefiung der Den Umrus der Keimscheibe K ‘ ‘
. urzer, Urwlrbel Chorda Noch mcht HOIISGIII. gmsggzgligéehatg mg" 5F}"lde“ G"3f,SPEE 3_]S -15-ltwas Eegen die fehlen als Plattevdellllich ab- ‘ . Embryo mess d F "'htk“"3 i elnfleschniirtblrnfbnni “,mner- bene der noch, in den esetzte Die Ke1_m- Gef5.lZsendothel- 6' ST] 31' lI'(_|I1C 311561 halb derselben ist ,, erjeni e Keim. doc)-, be.En1_-omast 11 gduflar. scheibeliegt réhren fanden sich G 9 P‘“"D° _d 91‘ 5C!lB 1181’ de{Med1_1llarplatten scharf b1s- scheibe reitet einge- latte mit dem Done?" niT£9nd5 in der ( LAEVEKB) I eci ua serotma kuitfarm abvesetzt“. Das etwa recht- sich ihre schaltet edullar- sack wie em Keimscheibe. An desSGra.fen 10.11 mm, sfinkrecht da- lmudale nde _er Keimscheibe winklig; ab- Bildung ' rinne. Deckel auf. der Stelle der pri- PEE- §“7.1l‘1,Ial;1- llY_Chm;ISe7 1st fast rechtwmklxg ventral- gebogener vielleicht Grufste Ein Stuck mitivenHerzanlage Esau‘? El: 113135 mill. w_irts umgebogen. Etwas kra~ Prim1tiv- vor Breite 0,517 K°Pfd31’m » N" E3712 VeTein' H F“ 8:5-1°-5:5 mflh nxa1_ von der pmgebogeuen sh-ejfem De, (very. bis 0,57 mm vom Dotter-1 zelte Zellen orlzontaldurchmesser P_art1e erhebt slch ein etwa Canalisneur- Text- 1 kleinst l = sack abge- Erste Anlage des deslnnenxaumes desEIes 11 gm ' ~ . . C. - n_ rm: er Wulst, der die entencus {'7 r f Bre1te(cl 1 1 trennt. 1 embryonalen CU- 7»518 mm. Embryonal- dorsale (geffnun des C ali d g“ 4 )~ IE ' loms im Gebiete I e + Bmmhsn-el var _ E . an s nrchsetzt schmglste ‘
3" “EA” h peurentencus umg1bt. Hxnter dle Ke1m- Stene "1 de, , der Herzge and.
er o_olbeha_ndlun_g dim verliuft als feine Kerbe scheibe in Mm d 1 Blutanlagen anden
mm, Kennschelbe his due Primitivrinne vorihmli ‘? er ’ ' h ~ hl‘ CS1‘ h
. .. . ) egf senkrechter KeIm- 1 W3 3°55‘: '9 ‘C z_um Ende der Prun1t|v- ,d1e Medullarfurche. Diese ver- Rich; 1 h »b In der Wand des "333 1154 mm; d|!?l!h- tieft sicl: ko fwlrts ' ‘mag: ‘ Sc 8‘ 6) ! Dottersackes Sam-finch - P nach Ma13- D1ePnmmv- o,494—o 38 , ' . e Brelte (let be der Wolb - - 1 1 . 1 ' ' ~ - “-“E und Brelte rmne 1st mm -1 . Kennstiheibe knnul er Medull 1 ' . - - 1 1 . . —. an den “P Btten. dlcht vor S-fbrmlg ge-
> der stark emgeen en Stelle krummt
, .°"“ . €11" hat sie e are ' 9:555 = tefe ‘und etwa den Gm ’ . ‘- mull‘: , ' 1 l
Ko fdarm- Die 1. H571 Vem-1'81
u‘-11¢ Kiemcn. gelegen, al_Jer nod:
32 Schnitte tasche ist P33715-
von lo p1 angelegt, Paange A°"en-
1. Kiemenarteriem
bogen.
Artt. umbilicales. Vv. omphnlo- mesentericae.
Gefllfle auf dem
Dottersack voll
von Blutk6rper-
chen.
Inn End- ertexchtaber
1 ‘ _ Skelet 1 Extrem1- .
‘men Amnion
Normentafel zur Entwicklungsgeschichte des Menschen.
Allantois
OI
Amnion Allan- Der Uterus, der das Ei enthielt, wurde dutch
geschlo_ssen,1 toisgang.} vaginale Exstirpation gewonnen.
von emem Ammon- ga ng mchts
1 gefunden. ‘1 1
hfihle
geschlossen, ‘wird kaudal sehr eng, reicht bls 1dicl1t an das ‘ Chorion i (Amnion- 1 gen )- Baucbgstiel auf der dor- salen Seite eine Strecke
weit vom l Arnnion uberzogen.
Kein Amnion- gang nach- weisbar.
Alla n- toisgang im B auch- stiel.
Allan- toisgang.
‘gewonnenes menschliches Ei in situ.
Fix.: 5-proz. erwiirmtes Formol.
F arbungz verschieden.
Schn.D. 15 14. _ Das Ei ist mit der Deciduakapsel geschmtten. Literatur: KEIBEL, Ueber ein junges o elxlmtidv er . . Anat. Ges., 1907. —FRASSI, L., Arch. f. mikr.Anat.,
, Bd. 70.
Embryonales Cblom noch nirgends angedeutet.
Zahlreiche ganz frische Kemteilungen.
Graf SPEE erhielt den Embryo von Dr. GLAZ- VEKE, der das Ei mitsamt dem Deciduauck in den Blutabgangen fand, die nach 5-wachentlichem Ausbleiben der Menstruation bei einer sonst regal- mflfiig in 4—wOchentlichen Intervallen meustruie- renden gesunden Frau ein etreten waren.
Literatur: Graf SPEE, eber ein menschlich Ei mit flach ausgebreiteter Keimscheibe. Mitt. f. (1. Ver. Schlesw.-Holst. Aerzte, Heft 11, Stick 10, I888. Ders., Beobachtungen an einer m lichen Keimscheibe u. s. w. Arch. f. Anat. I1. Phys, Amt. Abt., 1889. Ders., Neue Beobach- Xiggen u. s. w. Arch. f. Anat. u. Phys. Aunt.
t., 1
Abbil ungen von diesem Embryo sind in Ille Darstellungen der menschlichen Entwickl|Ings- geschichte flbergegan en.
Die Abbildung (N5. Fig. II) is! KOLLIIANII Handatlas der Entwicklungsgeschichbe ds Men- schen entnommen. Sie Ist nach einem Model! her estellt.
S (lam em1aryo|2_::len Salon: is: erst eine pa te in er e en der Herzanlnge Nur auf snem Schnitt fund nick. -'
t It . sleliflleine Verbindung dieser Spulte mit der.‘ “ " embryonalen Mesoblasthuhle Anflerdain
sich eine kleine Hobie (cf. T
man an die erste Anlage einer
denken kann.
Durch Laparotomie gewonnen.
Fix.: Mfinmnsche Fl ' keit.
Flirbung: Ahufl . -
Schn.D. to 1: quer. ‘
Literatur: PFANNKNSTIEL im
Geburtshilfe, herausgeg. von
_baden 1903. —— Kno
Jungen mensdzl. Embryn.
lo 9, 1903.
vlnww»-w
Uebersetzungsrecht vorbehalten.
Preface.
The Normal Plates of the rabbit were originally undertaken by me in 1896, in response to the in- vitation with which my friend, Professor KEIBEL, the Editor of the Series, honored me. It seemed to me that the rabbit offered particularly favorable opportunities for obtaining stages, which should be really nearly normal, i. e., representative of the median of the variations for each selected age. Accordingly I began collecting litters of embryos of known ages from ‘nine to twenty-one days, the ages selected being always either even days or half-days. Of each age at least four litters were secured, and of some ages six or seven. The next step was to select for each age by careful comparison of the specimens of that age with one another that litter of embryos which appeared nearest central. Out of this litter three embryos were taken for sectioning as representing the norm for that age. In a few cases the selected embryos were not all from the same litter. Next the selected normal or median embryos of all the ages were compared with one another to make sure thatthey formed a good progressive series. A typical embryo of each set of three was drawn and thus the series of figures on the plates was prepared. As will be seen the method
worked satisfactorily‘ on,-the whole, though the “normal” embryos of twelve and one half and of thirteen days.
do not fit perfectly into the series figured. V, V’ The three selected embryos of each stage were sectioned, one in the transverse, one in the-._sI_\g:‘i§fiail and one in the frontal plane. The three series of sections in each case have been added to the_'Har'e-lard
» Embryological Collection, where they will be always accessible to competent investigators. as
eveila mentaof the embryos have been obtained from the study of these series, and similar on ‘ ‘ ' howed thatthe three “nomial” embryos agree very closely with one another 2 Nortnentafelii zur Entwicklungsgeschichte der \\'irlu;-ltliiere.
Under these circumstances Professor KEIBEL consented to my having the collaboration of Dr. l£\\’i.\'<; TA \'i.oi:, and it is owing to his steady industry that the work is now completed.
The observations, upon which all the tabulations and descriptions are based, have been made by Dr. TAYLOR, who has been occupied \vith this labour for two years, during which he has devoted all the time, which could be spared from his duties as Assistant in my Laboratory. My own share has been that of a consultant. To Dr. TAYLOR therefore belongs the chief credit and a large share of the responsibility for this publication. . Most of the drudgery of getting together the titles for the Bibliography has also been borne by Dr. TAYLOR. We have endeavored to make the Bibliography complete as regards embryology, extensive as regards anatomy, but have included only the more important systematic and palaeontological papers, which seemed likely to be of interest to embryologists.
Harvard Medical School, Boston, Mass., February 8, I905. Charles S. Minot.
Description of Embryos pictured.
The embryos were in nearly every case fixed in ZENKER‘s fluid, as noted in the separate descriptions. The measurements and drawings were made from the specimens preserved in 8o°[,, alcohol, with one exception, the blastodermic vesicle of Fig. I. H. E. C. stands for Harvard Embryological Collection. The numbers in the column marked “Designation” in the Tables are the numbers of the series in this collection.
0 Fig. I (X 20). Surface view. Fig. Ia (X 20). Side view. Fig. 13 (X 5).
Blastodermic vesicle of rabbit removed from uterus 6 days, 11/, hours after coitus. Specimen was
i\'~iiiv.:l plat: \ -i1 tlir iii-iilnpnii-nt i-l the ralihit 1L--pus cuniculus L.). 3
compared with th<- lami : ihv eiitmlm-in nlw is \llL{llll}' ilIlL’l\'t‘l". This anterior portion of the shield is two-
layered, ectoderm and eiiloilcrlii. H. li. (,'., .\'o. 025.
m Figs. 3 (X 20) and 15 (X 5).
The drawing is a reproduction from another drawing made from a specimen which has since been cut. Embryo removed from uterus 71/‘, days after coitus. ZENKER fixation. Mesoderm measured 4.oX3.4 mm. The embryonic shield is pear-shaped. Hi<:NsEN’s knot, situated a little anterior to center of shield, is distinct. Notochordal anlage is visible as a more opaque band extending forward from HENsEN’s knot. Primitive groove runs from HENsEN’s knot to posterior end of shield. A more opaque area, corresponding to the extent of the inesoderm, stretches for some distance around the shield. This area reaches the anterior margin of the shield but does not pass in front of it. Over this area, beyond the boundaries of the embryonic shield, the outer ectodermal layer (trophoblast of HUBRECHT) is somewhat thickened. There is a distinct projection at Hi~:NsI~:N’s knot. The embryonic ectoderm over the region of the notochordal anlage is a little thinner than laterally in this part of the shield. The primitive groove is very shallow. H. E. C., No. 622.
Figs. 4 (X 20) and 16 (x 5).
Specimen removed from uterus 8 days, 6 hours after coitus. TELLYESNICKY fixation. Measured 1.8 mm. from anterior end of embryonic shield to posterior end of primitive streak. No segments. Embryonic shield broader at anterior end than at posterior. HENsEN’s knot is distinct: it is situated a little posterior to center of shield. The primitive groove extends from Hi«;NsEN’s knot to the posterior end of the shield, ending there in an opaque spot. The notochordal anlage is faintly indicated as a more opaque band extending forward from HENsEN’s knot. The ectoderm of the lateral portion of the shield, anterior to the region of Hr«:NsEN’s knot, is somewhat thicker than the median ectoderm over the notochordal a-nlage. This apparently marks the beginning of the medullary plate with a suggestion of a groove in the center. There
is no projection at Hi-:NsEN’s knot. There are apparently no blood anlagen. This specimen is only a little more advanced than that of Fig. 3.
I Figs. 5 (X 20) and 17 (X 5).
Embryo removed from uterus 8 days, 6 hours after coitus. ZENKER fixation. Measured 2.2 mm. from anterior end of medullary plate to posterior end of primitive streak. (The specimen was, however, a little bent, concave dorsally.) Medullary plate distinct, elongated, flat, slightly expanded at anterior end on each side in a curved manner. Posteriorly it surrounds HENsEN’s knot and merges into region of primitive s eak. Medullary groove is relatively wide and shallow. The notochordal anlage is visible through the
cove. The primitive streak is considerably shorter than the medullary plate. The primitive grooveiisy
HENsEN’s knot conspicuous as a circular opaque spot. Only one pair of segments is,e,l,ear§ .on both sides, but a second pair, posterior to the former, is clearly indicated though no the caudal side. The segments lie under the. narrowest part of the medullary than the anterior end of the plate. There are a few small extra-embryonic blood
' knot and merges into region of primitive strea 4 Nornieiitufeln zur Eutivicklungsgescliichte def \\'ll'b€“1‘l€"5-
Notochordal anlage is visible through medullary groove. HEi\'si2.\"s knot is distinct as a (‘lI‘L‘Lll.’ll' O]l.'l(]ll4' spot The primitive streak is short There are three distinct pairs of seglmntsi but the third l‘-'“i" l‘ “OT
- - - - n ' ‘ =, , I ‘.- completely separated on the posterior aspect. A fourth pair, anterior to these tlirec. IS lndlfltill WI 1 small and not clearly marked ofl‘. There are a few extra-enibryonic blood anlagen and primitive blood cells.
There is a very small coelom.
Figs. 7 (X 20) and 19 (X 5).
The drawing is a reproduction of another drawing made from the specimen before sectioning. The embryo was removed from the uterus 8‘/._, days after coitus. ZENKER fixation. Measured 3.4 mm. The medullary groove is wide open. There are six distinctly formed pairs of segments; the seventh pair caudad is nearly separated. Primitive streak distinct. The caudal end of the embryo in the region of the primitive streak is somewhat bent. For internal development, see Table No. 2, made from a study of the sections of this embryo.
I Figs. 8 (X 20) and 20 (X 5).
Embryo removed from uterus 81/, days after coitus. ZENKER fixation. Measured 3.2 mm. from tip of head to caudal amnion. There are eight distinctly formed segments. Posterior to the eighth, a ninth is almost completed. The cephalic end of the embryo is raised above the level of the surrounding extra- embryonic disk but dips ventral a little into the proamnion. The back is flat. The medullary groove is open throughout. It is considerably expanded in the region of the optic diverticula; a little expanded in the region of the hind-brain; nearly closed in the region of the future mid-brain. The walls of the medullary groove, between the segments, approach each other, but, posterior to the segments, diverge to form a space in which the remnant of the primitive streak is seen. Laterad of the segments, as seen by transmitted
light, is a narrow longitudinal light band, where there is a very small amount of mesoderm. Again laterad,
_ is a broader, darker area, where the mesodenn is thicker and incloses the coelom. Posteriorly, the segments
pas into an unsegmented band. The proamniotic area is distinct. The caudal fold of the amnion has
' The area of extra-embryonic ectoderm, which was attached to the uterus and torn ofl“ on the
' oval of the specimen, is quite large. It reaches anteriorly as far as the plane of the hind-brain. On ~ ‘_ view, the msodermal allantoic {old is plain. The pocket of the fore-gut is just discernible. The r is not to be made out on external examination. Compare, for internal development, Tables
and
9 (X 20). 21 (X 5) and 2n (X 5)-
‘ T from uterus 9 days after coitus. Znnxan fixation. Measured 3.4 mm. There are Thevoephalic end of the embryo bends ventrad beneath the level of the extra-
nearly 135° with the rest of the body, and is buried in the proamnion. Posterior
body is fiat. The place of entrance into the embryo of the vitelline veins is
day embryo, there is to be seen by transmitted light a narrow longi-
T ‘ " Again latcrad, a broader, darker area. Posteriorly the segments
n, which encloses the head, reaches approximately to the fold extenih cephalad more than one third the length of the " uwut except perhaps in the extreme posterior end. The e otic pits are just visible alongside of the hind-
qlisht under the hush. The heart tube is
A\VllI.n]al pl.ites of the rli,~ve]i.pineiit ut the rabbit (Lepus cuniculus L.). S
visible through the thin wall of this chamber. The fovea cardiaca or entrance to the fore-gut is very distinct. The ventral bend of the head begins just posterior to the heart. or in the region of the fovea cardiaca. The mesodermzil i\lli’1lllOlC fold is prominent. Compare, for internal development, Tables Nos. 6 and 7.
As compared with the 8‘._.—day eiiiliryo, this 9-day stage shows the following more important chanrres- there are ten distinct segments instead of eight; the head now bends ventrad forming a decided
rs ‘ ‘ 7
angle with the body; the proaninion surrounds the head; the caudal amnion is of much greater extent; the medullarv tube is closed nearly throughout the body; the otic pits are visible; the heart chamber begins to project.
I; Figs. io (X io), 22 (X 5) and 22a (X 5).
Embryo removed from uterus 9‘/, days after coitus. ZENKER fixation. Measured in a direct line from head to tip of tail 3.4 mm.; from head to bend of body 2.4 mm.; from bend of body to tip of tail 2.4 mm. The head of the embryo is bent at a point corresponding to the mid-brain approximately Ito a right angle. The body, also, at a point just posterior to the heart is bent to the same degree as the head. The caudal end of the body is twisted around sharply to the right so that it appears folded over fhe id- joining region. The optic vesicles are distinctly visible. There is a slight expansion of the roof ofthe hind- brain. The openings of the otic cups are distinct. The bent heart tube is visible through the thin wall. The mandibular and hyoid arches are clearly marked; the maxillary process barely so. are visible externally to the number of nearly twenty-three. The caudal segments are not with accuracy on external observation. Compare, for internal development, Tables Nos. 8 and 9. ._
Table No. 8 is a stage a little younger; Table No. 9 a stage a little older than the embryodaofifl
As compared with the 9-day stage, this 9‘/,-day embryo shows the follomlng mdfi changes: the head bend at the point of the mid-brain is clearly developed to the extant the bend of the body just caudad of the heart is now approximately right-angled '7 I caudal end of the embryo is twisted over to the right; the optic vesiclw are more are deeper, though still open; the heart is more prominent; the mandibular and h as well as a suggestion of the maxillary process; the segments are more nu - V
Figs. n (x Io). 23 (X5) and 23a (x 5).
Embryo removed from uterus IO days after coitus. ZBNIIII diameter viz. from vertex 1) of head to the most remote point on body head of the embryo is bent to an acute angle; the body is bentfln angle, while the tail end is twisted over sharply to the right. in thin expanded roof of the hind-brain has acquired a kite shape. T ganglion is clearly visible; the otocyst, perhaps both the 0! tinguishable. The oral cavity is wide open. The maxillary‘ tinct. There are clear evidences of a third arch posterior to clefts are plain. The mandibular arches do not meet at 4 tube is clearly visible through the thin periolrdial will; end of the body marks the beginningafore-limb bud. ginning hind limb bud. Segment: 4... visible for internal development, -Table No. IO. V
i)Vurtuishareiaadinthnunreo‘£tIra:G'nnfl1 .\'ormentat'eln zur Entwicklungsgeschiclitc tlcr \\'irbelthierc.
As compared with the 91/,-day stage, this lo-day embryo shows the following more unpuitztnt changes: the head bend forms an acute angle rather than a right; the hod_\' is so bent as to hate the surface of the embryo, corresponding in position to the original dorsal aspect, of relatively small extent; the otic vesicles are no longer open to the exterior; the head and body cephalad of the anterior bend of the trunk, including the heart region have clearly grown larger; a gill arch posterior to the hyoid has atipeztml,
as well as the first two clefts; the roof of the hind-brain has become kite-shaped.
él Fig. 12 (X to), 24 (X 5), and 24a (X 5).
Embryo removed from uterus IO‘].3 days after coitus. ZENKER fixation. Measured 4.8 mm. longest diameter. Vertex—brow, 2.2 mm. Vertex-neck, approximately 2.8 mm. The head bend is nearly right- angled. The neck bend has appeared. In the region of the fore-limb bud, the body is bent approximately to the extent of a right angle. The caudal end of the embryo is bent over to the right so far as to make nearly one complete turn. The optic vesicle is evident. The thin ependymal roof of the hind-brain is conspicuous: its kite shape is very distinct. Alongside of the hind-brain the trigeminal ganglion is visible. The maxillary process, mandibular and hyoid arches are prominent. The cervical sinus is indicated. In it, the third and fourth gill arches are distinguishable but not very conspicuous. The first and second external gill clefls are very clear, the third much less so. The oral cavity is wide open. The mandibular arches barely meet in the mid-ventral line, in part do not. The auricular region, the ventricular limb and truncus
amaiosus of the heart are easily visible through the thin pericardial wall. The fore limb buds form slight
projections in the region of the main bend of the trunk. The hind limb buds also form slight projections on the upper part of the turn of the caudal end of the body but appear a little less prominent than the a limb buds. Segments are visible externally to the number of approximately thirty-three. Compare, for vernal development, Table No. II. ‘ The more important changes in this lo‘/,-day embryo as compared with that of IO days are the ‘ :”the_neck bond has appeared but has progressed so far as to form an obtuse angle only with the ‘book; the caudal and of the embryo is rolled over to the right so far as to make nearly one the ependymal roof of the hind-brain is more conspicuous; the cervical sinus is now indi- I V gill arch and third external gill clefi have appeared; the fore and hind limb buds now
- Measured 5.4 mm. longest
vortex-neck nearly 3.0 mm. The brow projects beyond the pericardial tit end of the body by only a short interval. The head bend is firms an obtuse angle with the line of the back. The main bend of
Ihlil end of the body is bent over to the right. Shallow nasal
i vlaioles are distinct. The thin kite-shaped roof of the
' The maxillary process, mandibular and hyoid
I-1,fil1‘lIi!|'-1': it appear the third and fourth gill arches.
", third so, but evident. The mandibular
Normal plates lil the development of the rabbit (Lepus cuniculus L.). 7
The more important changes in this II-day embryo as compared with that of IO‘/, days are the following: the neck bend is more developed; the brow overhangs the heart chamber more, so that there is less space between the tail end of the body and the brow; the caudal end of the body is not rolled over to the right so much but makes nearly a half turn; nasal pits are now visible, as well as the openings of the lentic vesicles; the cervical sinus is more distinct; the third and fourth gill arches and the third external gill cleft are plainer; the limb buds are a little larger.
,3: Fig. 26 (X 5).
9
Embryo removed from uterus II‘/2 days after coitus. ZENKER fixation. Measured 6.0 mm. longest diameter: vertex-brow, 3.0 mm; vertex-neck, 3.6 mm. The brow projects beyond the heart chamber so far as to leave only a short interval between itself and the region of the hind limb buds. The head bend forms a wide acute angle. The neck bend forms an obtuse angle. There is a slight prominence in the region
of the mid-brain. The trunk is bent to approximately a right angle, but in the form of a gradual curuy ~ at a point a little caudad of the fore limb buds. The tail end of the body bends to the right totheetufl
of nearly half one turn. The tip of the tail is somewhat straightened. The lentic vesicles are closed. thin, expanded, kite-shaped roof of the fourth ventricle is distinct, as also the trigeminal ganglion. T130 nasal pits are rather shallow. The maxillary process, mandibular and hyoid arches are prominent. The I sinus is distinct. In it appear the third and fourth gill arches. The first and second externalgillclfi clearly marked; the third less so, but distinct. The heart chamber forms a projection undct-the region. The auricular region, ventricular limb and truncus arteriosus of the heart are clearly t‘-—
The fore and hind limb buds project. Externally there are visible approximately 37 or I (segments). Compare, for internal development, Table No. 13. _ I
The more important changes in this II‘/,-day embryo as compared with that of’
following: the head bend makes more plainly a wide acute angle; the neck band is mom‘
to approach more nearly a right angle; a slight prominence in the region of the mid I
the portion of the trunk between the fore and hind limb buds appears a little rs
lentic vesicles are now closed: the nasal pits are deeper; the cervical sinus 1
fore and hind limb buds are a little larger.
@ Fig- 27 (X 5)-
Embryo removed from uterus 12 days after coitus. -ZENKIR diameter: vertex-brow, 3.2 mm.; vertex-neck, 4.0 mm. The brow which the region between the nasal pits appears to rest. The hood is an obtuse angle. The main bend of the trunk onudadof than a right angle. The caudal end of the body bends overonffis The hemispheres are visible. The nasal pits are wide upon. _ ' ganglion are conspicuous. The maxillary pmow,- cervical sinus and therein the third and N cleft: are plain. The auricular and wall. Theifore and him! thuiruuiis ‘ *
Enlist-nIlliy'thezI, " I: I I I I 8 Normentafeln zur Entwicklungsgeschiclite ilcr \\'iil>c-ltlii.-rc.
a little so that it fmms an obtuse rather than a right angle; the nasal pits are deeper; the llllllIlllCHl curd
has become a somewhat more definite structure.
Q Fig. 28 (X 5).
Embryo removed from uterus I2‘/, days after coitus. ZENKER fixation. Measured in longest diameter
7_6 mm.: vertex-brow, 4.0 mm; vertex-neck, 4.0 mm. The end of the head projects well beyond the heart chamber. The head bend is a wide acute angle. The neck bend is nearly right-angled. The trunk, between the fore and hind limbs, bends gradually within the extent of an obtuse angle. In the region of the hind limbs the caudal end of the body is bent straight up and then turns to the right. The tip of the tail is bent a little outward away from the body: it is not far from the brow. The nasal pits are open. The outlines of the hemispheres are visible in front of the eye. There is a slight prominence in the region of
V the mid-brain. The eye, with the lens, is conspicuous. The thin roof of the fourth ventricle is evident. The maxillary process, mandibular and hyoid arches are large and prominent. There are on the mandibular and hyoid arches small irregularities, the beginnings of the tubercles of the external ear. The cervical
is marked only by a small hole. No third and fourth gill arches are recognizable. The first or auditory
‘T cleft is nowhere closed. No other gill cleft is clearly distinguishable. The auricles and the ventricular
region of the heart are easily seen externally. The fore and hind limb buds project quite prominently. rfirre limb bud shows a beginning division into two parts, an outer, broader and an inner, narrower and
H ‘part. The outer part is curved on its edge, but flattened from side to side: it is the beginning or
The hind limb bud shows no sign of division: it is, however, curved on its edge and flattened
distally. There is a quite distinct umbilical cord. Externally there are visible from the neck
bf'the.inil,- approximately 47 to 48 myotomes. Compare, for internal development, Table No. I 5. imipnrmnt changes, some of which are quite striking, in this 121],-day embryo as compared
’ e the following: the heart chamber appears relatively prominent; the neck bend
‘ angle; the trunk has straightened out considerably; the caudal end of the body
the form of a turn; the openings of the nasal pits are somewhat narrower;
so prominent; the tubercles of the external ear begin as described above;
T hole; the third and fourth gill arches are no longer recognizable; no
auditory; the limb buds are larger, the fore limb showing the beginning
‘lh hind limbs now mark the point of the upward caudal bend instead of
nearly in a direct line with the fore limbs.
coitus. ZBNIER fixation. Measured in longest diameter , The brow projects so for that the anterior nares face _ near. The head bend and neck bend are both fianidmdof the limbs forms awide obtuse “gnesga:”,un~m.na and slime to the right in
the imminent ngnslyiinuctnm,
Normal plates of the development of the rabbit 1Lepus cuniculus L.). 9
below the auditory cleft. There is no visible trace of a cervical sinus or of third and fourth gill arches. The milk line is clear though small. Both fore and hind limb buds show a division into two parts; a con- dition which is, however, better marked in the fore limbs. The distal part is curved on the edge, broader, but flattened from side to side; it is, in the fore limb, the beginning of the manus; in the hind limb, the beginning of the pes. Myotomes are visible externally from a point just cephalad of the roots of the fore limbs to the tip of the tail. Compare, for internal development, Tables Nos. 16 and 17.
The more important changes in this 13-day embryo as compared with that of 12'], days are the following: the head is larger and projects more; the trunk is considerably straightened though not much more than at 121/, days; the heart chamber is relatively less prominent, while the abdomen has become more prominent; the tubercles of the external ear are more distinct; the outlines of the mandibular and
hyoid arches have, consequently, become obscured; these arches also now meet below the auditory clan; .
there is no longer any trace of the cervical sinus; the milk line has appéared; the hind limb as wellli the fore limb shows the division described above; both limbs are larger. This I3-day embryo wm‘rIl'heI'
large in measure, though in degree of development it makes a very good stage between the I2‘/,-day-$6’ I4-day embryos. '
9? Fit: 30 (X 5)- U
The description is taken from a specimen closely similar to that figured and of Embryo of 14 days after coitus. Measured in longest diameter 10.6 mm.: vertex-brow, 5.6 mm.: 5.0 mm. ZENKER fixation. The head projects beyond the heart chamber so far mi: while the lies the latter, the brow and anterior nares nearly touch the umbilicus and umbilical cord. interval only separates the tail from the brow. The head bend is right-angled. The neck close obtuse rather than a right angle. The trunk bends gradually to the regim of the ‘" the caudal end of the body turns straight upward toward the head and nearly ' The tip of the tail is bent away from the umbilicus. The outline: of the hernisphers, able. The eye is prominent, the lens distinct, as also retinal pigment. There in region of the mid-brain. The thin expanded roof of the fourth ventricle closed below but has a wide opening. The pinna projects. The mlfiflaiy the mandible on lateral view. There is no distinct hyoid arch. The: beginning division into digits; the pes also, but perhaps a rim face mesad. The milk line is in part divided intoseplzu“ ' indistinct in the cephalic half of the trunk; in flteumhi development, Table No. 18. 1 ' T
The more important changes in this I4-.-dqv
ing: the overhanging head is nearer the pinna new projects a little; the V‘ 16!! Pmminent. the i the lilliofllllb ' V IO Nomientafelii zur Entwicklungsgeschiclite der Wirbelthiere.
4.4 mm. ZENKER fixation. The head projects far forward but the nares and brow are separated from tln~
- 1vil:1itc>i}l1ic|:atliscoI::t2:;:i::;i::ider[alb:eh:r;:r£)/al.d The mputh ffaces ‘downward toward the pericardial wall, from
The hind limbs are direct‘-ad vemrad rauenr tihs near) ridg t-ang ed. The neck bend forms an obtuse angle. with the fore limbs. The caudal end of ‘:6 bit: u-pulrjar toward the head; theyvare nearly in a direct line bent away from the body The abdomen is S y is . ent up between the hind limbs. The tip of the tail is mouth wide. The eye “gm! the lens is a ‘prominent as the thorax. The anterior nares are small; the prominent. The lid folds appear, though small. There are hair
anlagen visible on the maxilla and one large hair anlage under the eye. The pinna projects over the fihx:erf::ln:ti:‘d::o:':: od[;:'|l:ltlSDg- Tl'f:ie]i:;l:1i'Se ;.:‘:em:i1:1S1:da:d]dpes ridges, with shallow grooves between, indicating - a little caudad; the soles face mesad. There are
separate mammary anlagen. Myotomes are indistinct cephalad of the roots of the hind limbs. Compare for internal development, Table No. 19. ’
The more important changes in this I5-day embryo as compared with that of I4 days are the {Ono . . ' \V' mg: the head is now at a noticeably greater distance from the umbilicus; the neck bend has begun to straighten; the trunk has straightened so much that the hind limbs are directed ventrad more than upward toward the head; the abdomen has become as prominent as the thorax, which no longer projects in such
I slink‘ ing manner as in the younger stages; the lips have begun; hair anlagen appear on the maxilla and
‘mac’ the eye; the Plum‘ Projects more over the external auditory opening; digital divisions on manus
pes are more distinct.
Fis- 32 (X 5)-
- 7 6f 6 dike description is taken from a specimen closely similar to that figured and of the same age.
, V I ys alter coitus. Measured in longest diameter 16.2 mm.; brow-snout, 4.4 mm.; vertex-brow,
"°"53‘|l9¢k. 4.6 mm. Zsuxan fixation. The top of the head forms nearly a right angle at the
fie line of the face. The head bend at the vertex is essentially right-angled. The neck bend makes
angle. The head is somewhat elevated. There is a striking prominence at the vertex in the
V t The back -15 straight nearly to the level of the hind limbs where the body curves
until. ‘the short tail projecu ventrad in the median line between these extremities, which
the tip of the tail. The abdomen is more prominent than the thorax. The
(caudad). The snout projects a little. There are numerous hair anlagen
dlilfinot above the eye; one below. The mandible is not prominent. The lid folds
'V,fll‘>flIe enema] auditory opening. The manus and pes show distinct digital
‘ fin!’ larger. one on the median, originally upper, side smaller: the pes, four
dvltiflibns are connected. The palms look downward; the soles mesad.
‘ visible on lateral view. Myotomes are distinguishable only in T‘ : cord. Compare, for internal development, Table No. 20.
embryo as compared with that of I5 days are the follow-
Normal plates of the development of the rabbit (Lepus cuniculus L.).
Fig. 33 (X S)- The description is taken from a specimen closely similar to that figured and of the
same age. Embryo of 161/, days after coitus. Longest diameter, 17.6 mm.; brow-snout, 5.0 mm.;
vertex-brow 7.0 mm. ZENKER fixation. This I61/,-day embryo does not dlfier much from that
of 16 days except in some increase in size. The bends of the head, neck and caudal region are in essentially
the same condition. Compare the description of the 16-day embryo. The more noticeable changes are
the following: the snout projects a little more; the digits in manus and pes are somewhat more clearly separated; the pinna is a little larger and more pointed. There is still a striking prominence In the
region of the mid-brain. Compare, for internal development, Table No. 21.
Fig- 34 (X 5)- The description is taken from a specimen closely similar to that figured and of the same
age. Embryo of 17 days after coitus. Longest diameter, 21.0 mm.; brow-snout, 7.0 mm.; vertex- brow, 8.0 mm. Zsnxsn fixation. The angle at the brow is nearly right. The angle at the vertex
is obtuse. The neck bend forms a wide obtuse angle. The head is considerably elevated but projects ventrad of the body. The caudal end of the body curves around gradually until the short tail li between '
the hind limbs. The snout is quite prominent. The mouth and external nares face downward (candid); There are hair anlagen on maxilla and mandible, four above the eye, one below it and a few betweo 83$ mandible and the ear. These anlagen are numerous on the lateral and somewhat on the ventral of the trunk between the fore and hind limbs. There is a small elevation in the region of the The digits in both manus and pes are distinctly separated; five in the manus, four in the pa. The faces caudad, the sole mesad, nearly meeting its fellow. Compare, for internal development. V The few more important changes in this I7-day embryo as compared with that of 16'];
the following: the neck bend is further reduced and in consequence the head is more not such a striking prominence in the region of the rnid-brain; the snout and mandible are
prominent; hair anlagen appear on the trunk; the limbs are clearly larger; the digits
Fig- 35 (X 5). M The description is taken from a specimen closely resembling same age. Embryo of 18 days afier coitus. Longest diameter, 34.4 vertex-brow, 7.2 mm. Zanxan fixation. < This i8-day embryo does not show many important difioroucos new of which may be referred to; the former when compared with the lam: head is a little more elevated; the snout and mandible are anmowha ‘ developed; there is a general increase in size; hair anlagan are development of this I8-day embryo, Table No. 23. i I
Fig. 36 (X 5). 7 The description in Milton them a
age. Embryo of ao’da,'ys'afi¢sVoIfil'§e
vortex-h!ow,_i.’o mm V i 12 Normentafeln zur Entwicklungsgeschlchlfi def Wlrbemliera
considerably elevated. The tail projects directly ventrad. The external nares and mouth face in the
main caudad. The snout is quite prominent. The lids meet, Closing the eye- The head and trunk are well covered with hair anlagen. The palm faces caudad, the sole faces in part caudad
On both manus and pes the beginnings of the claws are indicated. Three separate ma are visible on lateral view.
Table No. 24.
in part mesad.
mmary anlagen The umbilicus is relatively small. Compare, for internal development,
There are only a few noticeable changes in this 20-da
y embryo as compared with that of 18 days, these are as follows: the snout projects a little more;
the bend at the brow is a little straightened; the head is a little more elevated; the eyes are closed; the sole faces a little caudad.
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Charles Sedgwick Minot (1852-1914)
Fellow in Class II, Section 3, 1882.
Charles Sedgwick Minot was born in Boston, December 23, 1852. His parental home, five miles from Boston, and comprising about thirty acres, stood on the edge of the forest area which then stretched from Forest Hills on the north to the Blue Hills and the Great Ponds in Canton and Braintree on the south. The region even now, as seen from the summit of Blue Hill, is largely a low forest, most of it of second and third growth, with areas of cleared land in which are small towns and villages, with farm lands about them. There are interspersed fine villas inhabitated by wealthy Bostonians, and most of the Forest is now included in the Metropolitan Park system and will be preserved. There are extensive low marshy flats, subject to overflow, along the Neponset River, and included in the forest there are large areas of swamp. Fine trees, elms, oaks, ash, beeches and pines abound in the region, but the trees in the forest areas are generally small. The flora and fauna are abundant and diversified. It is a stimulating region even now to a boy who has the capacity to see things and joy in seeing the wonder and beauty in nature. In Minot's boyhood the region must have been much wilder and hence more interesting than now. In such surroundings the boy grew up and early acquired the love of nature, the capacity of seeing, and the scientific curiosity to find out the meaning of the things he saw, which distinguished the life of the man.
He was a member of a large and well known family, with inherited wealth and distinguished in useful service. The usual course for a boy in his social class would have been to go through Harvard College and it is uncertain why he went to the Institute of Technology instead. The Institute had but recently been founded, it was just entering upon the great career which it has attained, and had the glamour of a new enterprise. At that time Minot could not have obtained in the Institute much stimulation in the study of natural science which from boyhood he had enthusiastically followed. He had already, at the age of sixteen, made his appearance in scientific literature by the description of the male of Hesperia Metea, a small butterfly captured in Dorchester and of especial interest because only the female of the species had been previously found. He derived probably a great stimulus from the meetings of the Boston Society of Natural History, which he regularly attended and took part in the discussions. He graduated from the Institute in 1872, at the age of twenty. The influence of the training he acquired at the Institute can be seen in his later life by the interest he had in mechanics and which led him to devise a number of laboratory instruments, among them the well known Minot microtome, which were characterized by simplicity of structure and admirable adaptation to the end in view. The micro-tome made it possible to cut thin serial sections of organs and is now, with slight and unimportant modifications, the instrument almost universally used for this purpose.
After graduating from the Institute he studied for a time with
Agassiz, but he found the most congenial atmosphere in the laboratory
of his friend, Henry Bowditch, who had returned from Europe in 1871
and established the first physiological laboratory in this country.
Minot was his first research student and found in the older man both
a congenial friend and an enthusiastic teacher. The period was one
in which teaching in medical science with the laboratory as a basis
was just beginning in this country. Previous to this the only laboratories, if they could be called such, in connection with medical schools
were the dissecting rooms, and in Bowditch's laboratory the torch
of science which was kindled in the ardent flame of the physiological
laboratory in Leipzig burned brightly. His work with Bowditch
turned his mind into channels which he afterwards followed, his early
interest in form and structure being never lost, although modified by
his study in physiology of the phenomena of life. In 1874 he published, in collaboration with Bowditch, a paper on the influence of
anaesthetics on the vasomotor system, and in 1876 a short paper on
transfusion and autotransfusion.
He went to Europe in 1873, working first at Leipzig with Ludwig
in physiology, then at Paris with Ranvier in histology, and at Wiirzburg with Semper in zoology. His was not the common fleeting visit
to these laboratories, but in each his stay was sufficiently long for him
to become acquainted not only with the laboratory work and methods,
but with the ideals which directed it. While at Leipzig under Ludwig's direction, he studied the production of CO2 in the active and
resting muscle. He returned to America in 1876 and conducted an
extensive series of experiments on tetanus, which was published in
1878, and in the same year received from Harvard University the
degree of Doctor of Science.
In 1880 he received his first academic appointment, that of Lecturer
on Embryology in the Harvard Medical School, and Instructor in
Oral Pathology and Surgery in the Dental School. At that time it
was unusual anywhere that instruction in a medical subject should be
given by a person who had never taken the degree of Doctor of Medicine, and the appointment of Minot was a distinct break in the
academic tradition. The appointment was due to the far-sighted
intelligence of Mr. Eliot, who recognized the ability of Minot and desired for the Medical School the influence which a man trained in the
traditions of pure science would exert on both the faculty and the students. The appointment was not welcomed in the faculty, and for a
long time Minot undoubtedly suffered from his supposed deficiencies.
The idea that a man teaching in a medical school should have some
knowledge of disease and be able to give an added interest to the subject
he teaches by pointing out the practical application of what is taught is
not altogether a faulty one, for medicine, certainly for the majority
of those entering into it is an art, but like all other arts founded on
science. In 1883 he was advanced to the position of Instructor in
Histology and Embryology, and this subject was given a satisfactory
place in the curriculum, though it was a number of years before laboratory instruction in this subject was made obligatory and a definite
part of the course. In the year 1887 he was advanced to the position
of Assistant Professor. After the usual term of five years he was made
Professor of Histology and Embryology, and when the James Stillman Professorship of Comparative Anatomy was founded he was
transferred to that position. Upon the death of Doctor Dwight,
in 1911, the subjects of Anatomy and Histology were placed together,
and in 1912 he was made Director of the combined laboratories.
As a member of the faculty Minot was always outspoken, clear and logical. He never sought to obtain any end by suavity or the claims of friendship. His arguments were always keen, definitely to the point in view which was strongly presented, sometimes even too much so. There is apt to be some suspicion in the minds of men when a policy advocated is too clearly presented; it is not flattering to those holding the opposite view. The general discussions in medical faculties do not suffer from clear and logical statement, and Minot's presentation of a subject was in marked contrast to that usually heard. While it often took a long time for men to agree with him, and he usually obtained what was desired, there was never a suspicion that the ends in view were personal and selfish. His active support could always be obtained for any measure looking to the betterment of instruction and the advance of scientific interest.
He was in all respects an admirable teacher; as a lecturer simple
and clear, interesting, often enlivening the subject by shafts of keen
humor, and in the laboratory stimulating, always insisting that the
students should cultivate the faculties of independent observation
and judgment. Minot was the first to introduce into the medical
schools of the country the laboratory method of student instruction,
and the way is never easy for the pioneer. It was a method new to
the students, for the men entering the medical schools seem to acquire
neither in the home, nor in the schools, nor in the colleges sufficient
training in the methods of science. Minot lived to see the modest
beginning of this method of teaching, which he made under most
unsatisfactory conditions in the old Medical School on Grove Street,
become the dominant method used alike in the pre-clinical and
clinical branches.
Minot was an excellent director of a laboratory. His laboratory
was always orderly, giving one entering it the impression given by a
well ordered household. He devised a method of giving each student
the use of a microscope by having him pay the school a small sum,
which sufficed for their upkeep and renewal. He early began the
collection of embryological material, the embryos being cut in serial
sections and arranged in suitable and permanent steel cabinets which
he devised. In the course of time this grew into an unrivalled collection, serving an admirable purpose, not only in teaching, but in
research also, as is shown by the number of researches based upon
the material of the collection. The collection was freely used by the
other departments of the school, so that any question arising which
was wholly or partly based upon the course of embryological development could be here studied on admirably preserved material. Minot gave much time and thought to the plans for his new laboratory at the school and here first put into effect what he described as the laboratory unit. The unit of the teaching laboratory is a room for twenty five students, provided with the essential instruments for laboratory work and under the direction of one instructor. The entire class
comes together for lectures and demonstrations. The method renders
it possible to extend a laboratory indefinitely without confusion,
provided the necessary space and instructors are at hand. Minot
had moreover an excellent business sense and made the small budget
at his disposal cover a wide field.
He was a prolific writer, his most striking contributions being not
in small single researches, but in more extensive publications in which
he brought together and made more serviceable the accumulated
knowledge of a subject. Sometimes, as in the case of his well-known
Human Embryology, the work covered a large field. This large and
comprehensive work, the result of ten years labor, was in no sense a
compilation, but was based on his personal knowledge of facts,
expanded by the knowledge contributed by others. The American
edition was published in 1892 and a German edition in 1894. Of this
work His, at that time the leading anatomist of Germany, says,
" Minot's work is at present the fullest embryology of man which we
possess, and it will retain its value as a bibliographical treasure-house
even after its contents in many parts have been superseded." He
early became interested in the subject of growth, the stimulus
probably coming from Bowditch, who was carrying on his well known
studies on the growth of school children while Minot was working in
his laboratory. His first paper on the subject, 1878, was "Growth
as a Function of Cells" which was quickly followed by another
"On Certain Laws of Histological Differentiation" and in the same
year he presented in an address "On Conditions to be Filled by a
Theory of Life" an outline of his future work. There were many
papers on the subject of growth and senescence, the whole being
brought together in a book "The Problem of Age, Growth and Death"
based on lectures at the Lowell Institute, March 1907. This work
has been so well analyzed by Lewis in his Memoir that I quote from
it. "Senescence and rejuvenation were studied by tabulating the
weights of guinea-pigs from birth to old age, and of rabbit embryos
up to the time of birth, using weight as a measure of growth. The
conclusion was drawn that the fertilized ovum is endowed with an
enormous power for growth, over ninety-eight per cent of which has
been lost at the time of birth. The remaining two per cent is largely
exhausted in infancy. Therefore he concludes that "senescence is at its maximum in the very young stages and the rate of senescence diminishes with age." He protests against "the medical conception that age is a kind of disease," chronic and incurable, of any such nature
as intestinal intoxication or arteriosclerosis. On the contrary he finds
that it has a cytological cause, equally operative in the lower animals
which have neither intestines or arteries and in man; and he ascribes
senescence to the increase and differentiation of cytoplasm as compared
with nucleoplasm.
In 1901 he proposed "the new term cytomorphosis to designate
comprehensively all the structural alterations which cells, or successive generations of cells may undergo, from the earliest undifferentiated stage to their final destruction." His latest works on this subject, aptly characterized as "thoughtful and suggestive," refer
to cytomorphosis as a most promising field for further study, and at
the time of his death, plans had been made for careful investigations
to test the validity of his cytomorphic hypothesis concerning age."
Of Minot's shorter contributions perhaps the best known is a paper,
1900, "On a hitherto unrecognized form of blood circulation in the
organs of Vertebrata." Everyone was familiar with the differences
in the thin walled capillaries running in the connective tissue of most
organs, easily compressible, their calibre varying with the activity
of the circulation, and the vessels in the liver which were wide, closely
applied to the parenchyma and whose calibre cannot easily vary.
He regarded such vessels not as capillaries but as sinusoids, showed
their manner of development and the organs in which they were found.
Minot was greatly in demand as a giver of addresses and these cover
a wide range of subjects. His style was vigorous, graceful, the
subject enlivened by humor, sometimes with a little satire, and
always interesting. They were collected and issued in a German
translation under the title " Die Methode der Wissenschaf t und
andere Reden" - Jena, 1913. Altogether he has published more
than one hundred and eighty notes and papers, including his addresses.
In 1912-1913 he was Harvard Exchange Professor at Berlin and
Jena, and used the position largely in bringing to the attention of his
German colleagues the amount and character of the contributions of
American investigators. The position was very enjoyable to him,
for he renewed and extended his wide acquaintanceship with the
German men of Science.
Minot possessed a wide acquaintance with scientific men here and
abroad; he was constant in his attendance on scientific meetings,
taking part in the discussions, and occupying a prominent place in the conduct of societies. He was at different times chosen President
of the Naturalists, the Anatomists, the American Association for the
Advancement of Science, and the American Academy of Arts and
Sciences, and was frequently a member of the councils and of important committees. He was an active or corresponding member of many of the learned societies of Europe, and was honored with the L. L. D. of Yale, 1899, Toronto, 1904, St. Andrews University, Scotland, 1911, and Sc. D. of Oxford, 1902.
No account of Minot would be complete without some mention of
his beautiful country home at Hyde Park, the region over which he
must have rambled as a boy. The house was a plain one, roomy,
furnished simply and in exquisite taste, and stood near the road,
the land sloping away from it toward the south and west to a low
lying wood, through which a small brook ran. The whole place was
in keeping with Minot's character. It was well ordered in its plan and
keeping. The trees he planted were properly placed, selected with
care, and were fine specimens of the species. He bought a large number of seedlings of many varieties and as these grew he selected from
them the finest specimens for planting. Every tree and shrub was
well cared for and showed the effects of this in their health and vigorous growth. The garden, formal in design, with well kept grass paths,
was at the foot of the slope, some distance from the house, and entered
through a small arbor covered with climbing roses. Though formal,
it was not severe and contained good specimens of the usual annuals
and perennials and many rare plants. The two plants to which he
gave most attention were irises and peonies, of each of which, but
particularly of the latter, he had a large and rare collection. There
were several hundred varieties of peonies, every plant showed intelligent care, and his system of cataloging and labelling was as simple
and complete as the system in his laboratory. It was a great joy
to go with him among the blooming peonies and see their beauty
through his observant and well trained eyes. It is not an easy thing for
an amateur gardener to obtain the prizes of the Massachusetts Horticultural Society, but Minot obtained prizes both for peonies and for
the general excellence and beauty of the garden as a whole. The
grounds and garden showed that highest art by which art is concealed
and every plant grew and bloomed as though for the mere joy of living
under conditions in all respects the best. There was a profusion of
bloom from the earliest spring bulbs to the late chrysanthemums.
Many of his plants had a personal history which he would delightfully
relate, as having been procured under unusual conditions, or being
transferred to a more suitable situation, or having developed some
uncommon and interesting characteristic. He was most generous
with his plants, delighting to assist young beginners in horticulture.
Through the wood along the brook there wandered a simple path,
along the sides of which were many flowering plants collected from the
swamps and fields, each in the situation best adapted for its growth
and display ; as a mass of dog toothed violets at the base of a decayed
stump overgrown with moss, or a yellow mass of marsh marigolds
intermingled with the beautiful though maloderous swamp cabbage.
I first became acquainted with Minot through the series of excellent articles on anatomy of the uterus and the changes associated with
pregnancy, which were published in 1886 in the Handbook of the
Medical Sciences, to which I also contributed. He was at all times a
delightful companion, always loyal as a friend, sympathetic and
helpful. He never hesitated to testify to his friendship. He was in
all things generous, in helping younger men both materially and otherwise, a hospitable host, one who knew how to make a guest feel that he contributed to the pleasure of the host. He spoke well on most
subjects, as an impromptu speaker thought came clearly and quickly
and was expressed in simple language and without hesitation.
In June, 1889, he married Lucy Fosdick of Groton, Mass., in whom
he found a sympathetic, helpful companion, and those who knew
Minot will always associate her in their thoughts of him.
Science has been enriched by his life; in devising instruments which facilitated work, in teaching and inculcating good methods, in the
research he personally conducted, and in his masterful method of
presenting the work of others he added to the sum of knowledge and
made its pursuit more profitable. He was a good patriotic citizen
with high ideals of civic duty. He increased the joy of living by bringing to many people a richer and fuller sense of the beauty of living things; the world is a better place by his having lived.
In the preparation of this Memoir I have made use of the Memoirs by Frederick T. Lewis, by H. H. Donaldson, and by Charles W. Eliot.
W. T. Councilman.
Plate 2
Plate 3
Proceedings of the American Academy of Arts and Sciences, Volume 53.
