Talk:Harvard Collection

TIIE HARVARD EMBRYOLOGICAL COLLECTION.

CHARLES SEDGWICK MINOT, LL.D., D.Sc.

Received for publication June 29, 1905.

The collection of serial sections of embryos in the Embryological Laboratory of the Medical School has now grown to sufficient size to render clear the scope of the collection, and to enable us to form some estimate of its usefulness in facilitating study and promoting research. At this date it comprises nine hundred and thirty-seven series. The plan which has been followed was drawn up in 1895, and its execution was begun in January, I896, and since that time work on the enlargemeent of the collection has been unremitting, although, ofcourse, many other duties had to receive attention in the laboratory; the preparation of serial sections being only one of the things to be attended to in the course of the regular work. Our means have not hitherto permitted us to employ assistance which should be devoted exclusively to the development of the collection. Inspiteofthesedifficulties, however, the actual achievement may, I think, be regarded as encouraging.

AMNIOTA. Man. Cat. Rabbit. Pig. Sheep (not yet begun). Opossum. Chick. Lacerta. Chrysemis (not yet begun). Eutaenia (not yet begun). Squalus.

ANAMNIA. Rana. Amblystoma. Necturus. Lepidosteus. Amia. Ameiurus. Salvellinus. Batrachus. Torpedo. Petromyzon. Amphioxus.

It should be mentioned that in addition to our regular types we have a few others represented by a few series which have been prepared in connection with special researches, Such supplemental forms are the dog, guinea-pig, Caluromys, Torpedo marmorata, Raja clavata, and Scyllium canicula. The number and variety of these series will doubtless increase hereafter, The plan is, further, to obtain of each of these typical species a complete series of embryos, to select systematically graded stages, and of each stage, so far as possible, three identicalembryos. Thethreespecimensthuspickedoutare intended to be cut intoserial sections, one embryo transversely, thesecondsagittally,andthethirdfrontally. Bythismeans views of the structures in the embryo, according to the three planes of space, can be obtained, and at the same time there is the advantage of some indication of the variations which occurfromembryotoembryoinagivenstage. Inorderto carry out this plan it has been indispensable to resist the frequently recurring temptation of cutting up a fine embryo, which did not fit into the scheme adopted, for this would delay indefinitely the completion of the plan. Series of sections, gotten up according to this scheme, may be regarded as normal series, illustrating the development of a particular type, and through that type the development of the classto which itbelongs. The various forms selected can be compared with one anoth,er, and thus there is always onhandmaterialforcomparativeinvestigation. Itisevident that such a collection as this could not answer foral the requirements of research, but serves well to enable one to make a preliminary study of the development of any organ or tissue, to find out exactly at what stages changes may be occurring which it is desired to investigate more closely, and to give more or less information, as to the nature of those changes. Inactualpracticeithasbeenfound,andwill surely continue to be found, necessary to make many special preparations for special purposes, or to follow out certain details of modification, which may not be well illustrated with the material in hand, or which can be better brought out by other methods of preservation and of staining than thoseusedforthespecimensinthecollection. Inspiteof althese limitations, however, the collection has proved itself already of substantial use for purposes of embryological research. SofarasIamaware,noothercollectionofthis kinidhasyetbeenattempted. T'iereare,ofcourse,inthe possession of various individuals, and in a few laboratories, collections of serial sections of embryos of considerable size andgreatvalue,butunlessIam mistakentheHarvardcol- lection is the only one which was planned to be perfectly systematic, and which has been actually built up on the systemoriginialyproposed. Inpracticethesystemhasbeen slightly departed from in certain cases, where the material at handrenderedthisindispensable. Thisischieflythecase with the series of human embryos, now 42 in number, for obviously the embryos of the human species inust be taken as they are obtained, and cannot be selected as they are desired.

The collection is intended to become a sort of a cyclopedia of vertebrate embryology to which one can turn at any time and get the desired information as to the principal featuresofdevelopmentofanystructurewhatsoever. Itis hoped, therefore, that the laboratory will be regarded as a useful central place to which persons may come who are seeking embryological information, or who desire for the completion of their original researches the use of a larger material than they could command by their owIn individual unaidedefforts. Inacollectionsoextensiveasthishasnow become, there is abundance of-material for many workers, and there is never likely to be any great clashing of interests intheuseofthespecimens. ItiswithpleasurethatInote thatseveralprofessorsofother universitieshave alreadyuti- lizedthe opportunities which we are able to place attheir disposal, and it is hoped that the number of these will increasefromyeartoyear. Themostliberalpolicyinthis regardissurelyforthebestinterestsofal,and best calculated to promote the higher interests of science.

It is evident that, as a rule, the collection must remain in the laboratory and be used there, for its usefulness for reference and study would be impaired if the specimens which areneededcannotbefoundathand. Toalimitedextent, perhaps, the practice may be accepted of sending specimens to workers elsewhere, and this has been done, opossum mate- rial having been sent to Prof. C. F. W. McClure, of Princeton, and material for the study of the development of the human jaw sent to Prof. Edward Fawcett, of University College, Bristol,Eng. Attheendofthisarticlewillbefounda listofpublished researcheswhich have been basedchiefly, orinpart,uponthecollection. Itispleasanttonotemuch generous assistance which has been given us, especially in the wayofaidingettingthematerial. Thelaboratoryhasbeen specially indebted in this respect to Prof. S. H. Gage, of Cornell, for specimens of the lamprey; to Prof. R. G. Har- rison, of Baltimore, for lizard embryos; to Professor McClure, of Princeton, for opossum material; to Prof. Anton Dohrn for a fine set of torpedo embryos; to Prof. A. C. Eycleshy- mer, of St. Louis University, for various material; to Prof. W. A. Locy, of Northwestern University, for necturus; to Prof. Karl Peter, of Breslau, for lacertas; to Professor Dendy for several sphenodons, and to several other generous friends. Our human embryos we have received chiefly from practi- tionersinBostonandtheneighborhood,toalofwhom our mostsincerethanksaredue. Amongthesehumanembryos are some of the very finest, and scientifically most valuiable, whichhavebeenasyetobtainedforscientificstudy. Agift of two htindred dollars from Dr. \Valter G. Chase enabled us toemployaid,whichcontributedverymuch tothegrowth of the collection.

It seenms desirable to describe some of the technical methods used in the preparation and cataloguing of the series.

With regard to fixation of the specimens we have con- tentedourselveswithemployingthestandardreagents. Of' these, the three which we have found most useful are Zenker's fluid, asaturated solution of corrosive sublimate, andtenpercentformalin. Zenker'sfluidhasprovedvery satisfactoryfortheembryos ofaltheAmniotaand forthe youngstagesofAmphibiaandfreshwaterfish. Itcannot, however, be used with very large specimens, as it has no great penetrating power. It does not work satisfactorily withtheembryosofsaltwaterfishes. Forthesewehave foundthesaturatedsolutionofcorrosivepreferable. Even better results are obtained, according to our experience, with theembryosofElasmobranchswhen fivepercentofglacial aceticacidisaddedtothecorrosive. Thisaceto-corrosive mixture has been very satisfactory also with reptilian embryos. Forlargerspecimensweconsidertenpercent formalin preferable toeverythingelsewhich we have tried, and there sults of thisreagenthavefarsurpassed ourexpec- tations,forwe have even observed fairlygood karyokinetic figuresinniaterialpreservedwithit. Itistheonlyreagent with which we have obtained even tolerable preservation of the more advanced stages of the opossum, although the early development of the epitrichium and horny layer in this species prevents the penetration of the ordinary preservatives except inveryearlystages. Formalinweusealmostexclusively forhumanembryos. Itiseasyforapractitionertoobtain thismixture,ortomake itwhenhesecuresahuman embryo, and its use being so very simple, this reagent finds favor amongphysiciansingeneralpractice. Formalin specimens contract when transferred to alcohol, but this contraction may be largely reduced by putting the specimens in Muller's fluid for forty-eight hours before placing them in alcohol.

It seems not to be really necessary to wash the specimens whicharepreservedinZenker'sfluid. Allofourembryos are transferred gradually to alcohols of increasing strength, but they are never put in alcohol of greater than eighty per centuntiljustbeforetheyarecut,when theyaretransferred to ninety-five per cent alcohol for twenty-four hours to harden them. Iconsidertheuseofstrongerthaneightypercent alcohol for permanent preservation of embryos very unde- sirable. Inthecaseofolderembryositcausesashrinkage, andinthecaseofalembryositisaptto makeatrue final hardening, for the purposes of embedding, difficult or even impossible.

For the storing of embryos a convenient method has proved to be the use of a combination of small vials and large jars. A singlemuseum jarisusedforonespeciesonly,and islabelledaccordingly. Theembryosaresortedaccording to stages, methods of preservation, etc., in cylindrical vials, whichhave flatbottoms,sothattheywillstandupright,and straightsides(Fig.i). Thesizewehaveusedmostmeasures sixty millimeters in height by twenty millimeters in diameter. Vials with mouths narrowed are excessively inconvenient. Thevialsareclosedwithplugsofabsorbentcotton. When necessary a slip of paper, bearing memoranda concerning the specimens in a vial, is put in alongside the plug of cotton, bywhichitisheldinplace. Thewritingontheslipis turned towards the outside of the vial, so that it can be read withoutdisplacingitordisturbingthespecimens. Dataare written with a lead pencil, but when a more permanent record isdesired itisbetter to use Higgins's waterproof ink. A dozen or more vials may be kept together in a single jar.

In regard to the selection of stages we have had, of course, in the case of each new form to proceed somewhat arbitrarily, but experience has shown that so soon as the embryo is suf- ficientlyadvanced for its length to be measured, one may say that an addition of one-fifth or one-sixth to the length corresponds to a sufficient advance in development for the embryotobesaidtohavepassedintoanewstage. Atthe same time such an increase in length does not bring about so great an alteration of structure as to render it difficult to tracethenatureofthechangewhichhasgoneon. Onthe other hand, it is occasionally necessary for some special study to have the stages closer than this, but the stages, arbitrarily fixed by the rule indicated, we have found by experience to be sufficiently close to one another to afford commandofthewholecourseofdevelopment. Asstated above, we have endeavored to procure of each of these stagesthreespecimensalikeinlength,butwe havelearned that it is also very desirable to get them as nearly as possible alikeinformandexternalproportions. Ifthisisdonethe internal development is usually very much the same in the threerepresentativesofagivenstage. If,ontheotherhand, we have three embryos, say of a pig, which are of the same length measured from the vertex to the tail, but differ from one another in external form, we shall find that they vary considerably in their internal organisation.

It is desirable to have a drawing or a photograph of every embryo which is sectioned. In practice we rely chiefly upon drawings, but we think photographs would be preferable, and we should have made them were it not that photography in our present cramped quarters is so incon- venient. Whenwemoveintoournewlaboratorywehope to substitute photography for the drawings upon which we depend at present.

Almostalofourspecimenshave beenstainedintotobefore they were embedded, the stains upon which we have chiefly relied have been alum cochineal and borax carmine. At first we contented ourselves with a single stain, but we now habitually employ a counter stain as well, the three chief counter stains which we use being orange-G, Lyons blue, andeosine. WeconsiderboraxcarmineandILyonsbluea particularlyusefulcombination. Itsometimeshappensthat thecochinealorcarminestainistoofaint,and insuchcases our practice has been to stain the sections on the slide with saffranine. Occasionally,butnotoften,wehavestaineda series with Haidenhain's iron hematoxyline, counter stain- ing with orange-G.

It is important to have uniform rules for the making of sectionssothattheymaybe insimilarorientationinalthe series. Toaccomplishthisourserieshavenearlyalbeen cut according to the following directions:

DIRECTIONS FOR CUTrING SElRIAL SECTrIONS OF E:NM13RYOS. (NOTE. Theloweredgeoftheribbonistheonetotheleft,wvhiCItlReyobserverhasthe object betwveen himself anid the knife.) I. TransverseSeries: Normal thickness ........................... io It. Dorsal surface to be towardls the lower e(dge of the ribbon. Series to begin with the head. In cutting, the left sidle of the emlbryo must strike the knife first. 2. SagittalSeries: Normalthickness. Smallcemibryos............loa- Medium embryos. I /1. Largeemnbryos............ 20/1. The head of the embryo to lie towards the lower edge of the ribbon. Series to begin with the right side. In cutting, the ventral si(le of the embryo imiust strike the knife first. 3. FrontalSections: Normiialtbickness. Smallemibryos............loP. Mediumembryos. .I5t Largeembryos . ....20/X. The head of the embryo is to be towards the lower edge of the ribbon. The series is to begin with the ventral side. In cutting, the left side of the einbryo must strike the knife first. MOUN IING: Leavespaceforthelabelatthelefthandendoftheslide. Keepthe sectionsintheordercut. Arrange the montheslidesinthesequence of ordinary written lines. Care must be taken to make the rows of sections as straight as possible.

All of our series are mounted on slides, forty by seventy- six millitneters, and we now insist upon the slides being from I.8to2millimetersthick. Thethinslides,whichhaveso long been favorites, are very fragile and often get broken. The thicker slides are much less subject to accident, and have no disadvantages, so far as I know, except that of not permit- ting the use ofa very short focussed condenser with the microscope. Thisdisadvantageseemstobemoretheoretical thanreal. Thesizeofslideadoptedwas chosenaftercon- siderable deliberation, and seems to me, on the whole, to be the most convenient for such series as we have gathered. On this slide we use a standard size of cover-glass, one measuringthirty-fivebyfiftymillimeters. Thesectionsare mounted so as to leave one end free for the label, which is placedasshownintheaccompanyingfigure(Fig.2). Onthis label the name of the species, direction, and thickness of the sections and their staining are recorded. The label also carriesthenumberoftheseriesand alettertoindicatethe positionoftheslideintheseries. Thisismerelyforfacili- tatingthequickarrangementoftheslidesincabinets. And finaly,thelabelindicatesthenumbers ofthe sections, there being recorded for each row of the sections the number of thefirstandofthelastsectioninthatrow. Thismakesit veryeasytodeternminequicklyby counting from eitherend oftherowtheexactnumberofanysectionintheseries. In order to have permanent labels we use for writing either Stevens'sblue-blackwritingfluidorHiggins'swaterproofink. Iprefertheformer.

When researches are published, in which any figures are given, taken from any of our sections, we require that the number of the series and the number of the section should be given, together with the figure. In this way the original evidence of the author's observation can be quickly found, and his statements easily verified. In consequence of this rule the collection isbecoming more and more comparable to a collection of types, such as systematic zoologists value so highly. Itistobehopedthatthispracticewillextendto other laboratories, so that the custom may become general of preserving, in each institution, in a readily accessible form, the material which has served as the basis for researches, thus renderingpermanently possibletheafterverification of theactualobservations. Certainlynoinvestigatorwillwork less accurately because he knows that his specimens may be restudied by his successors in order to test the reliability of his observations.

In regard to the cataloguing it is only to be remarked thatwehaveofcourseadoublecatalogue. First,abookin whicheachseriesisenteredinnumericalorder. Foreach series the following data are entered: the species, size, age, locality, drawing, nature of the sections, date of preservation, dateofsectioning,method ofpreservation,staining,mount- ing. Thereisalsoacolumnforspecialremarks. Second, there isa card catalogue inwhich the series are grouped first, according to species; second, according to the stage; and third, for each stage according to the plane of section, the order being always for each stage, transverse series first, sagittal second, frontal third. The arrangement of the series in the cabinets agrees with the card catalogue, follow- ing precisely the same order, so that by consulting the card catalogue itmay be seen at once precisely what material we have of any given animal, and the position of the card indi- cates also the position of the series in the cabinet.

In regard to the storing of the series a few words may be added. We have tried both the smallwooden slideboxes, and also the pasteboard trays,which are stacked together and kept in boxes, the latter of the type so much used in Germany, but neither of these have we found convenient. For several years we relied upon wooden cabinets with small trays, which could be pulled in and out, but these cabinets even when they are made with great care are not wholly satisfactory, because no method has yet been devised of making the trays simplyand cheaply,yet in a formin"whichtheywillnotwarp. Byfarthebesttrays, however, which we have succeeded in getting are those whicharemadeofCaliforniaredwood. Theseholdvery well, and change their shape so slightly that they go out and in their places quite smoothly, which is more than we can say of trays made of any other vood which we have tried. But there is another objection also to wooden cabinets- thedangerfromfire. Ifafireshouldoncestartinthem,it mighteasilydestroytheentirecollection. Another objection to wooden cabinets is that the wood forms a cloudy de- positonthesurfaceoftheglassslides. Iftheprepara- tions are left for several months it becomes necessary to clean off the slides and cover-glasses to render them fit for microscopicexamination. Theseconsiderationshaveledus toadopt a metal cabinet,which has been speciallydevised forourneeds. Itismadeofsheettininsuchamanner that the trays are very compact, are absolutely interchange- able,anidtakeupaminimumamnountofroom. Thecon- struction adopted issuch thatthetendencytowarp isentirely doneawaywith(Fig.3) Thetraysarealjapannedso that they do not rust, and we slip a bit of white paper into eachtraytomakeabackgroundforthesections. Each tray is, moreover, furnished with a litle label holder, and they are put together in cabinets of thirty trays each, the trays themselves being of such a size that they will hold twenty-four of the ordinary slides, three inches by one. Moreover, the cabinets themselves are so devised that they can be stacked one on top of another, taking up a minimum amount of room. We devote a vertical column of these cabinets to a species, and simply interpolate from time to time a new cabinet in the column as the growth of the col- lection may render necessary. The cabinets are made by Peter Gray & Co., of Union street, Boston, and are now kept in stock by several of the dealers in microscopical sup- pliesinthiscountry. Theycostonlyatriflemorethanthe wooden cabinets,andare,accordingtoourtrialofthem, certainly to be preferred to any other form of cabinet which we have tested.

The account of the Harvard Embryological Collection would be incomplete without a word of appreciative acknowl- edgment of the zealous aid given by the members of the laboratorystaf. Thisisespeciallydue Dr.Alfred Schaper, now professor at Breslau, who co6perated very extensively in the foundation and early development of the collection, and to three of our present members, Drs. J. L. Bremer, F. T. Lewis,andE.Taylor. Allofthesegentlemenhaveusedthe collection for important investigations which they have made.

The following tables show the present extent of our collec- tion. Theyaresoarrangedastobeself-explanatory. For eachspeciestherearefourcolumns. Thefirstgivesthe lengthorage. Thesecondisforthetransverseseries,the thirdforthesagittal,thefourthforthefrontalseries. The numbersarethenumbersoftheseries. Thus,inthefirst table of human embryos, the second specimen is an embryo offourmillimetersinlength. Itwascutintotransversesec- tions,andtheserieswasenteredasNumber714. Itwillbe noticed that the most nearly complete set of series which we haveisofTorpedoocellata. Withveryfewexceptionsal our series up to the present are of embryos not of the earlier stages, which itis hoped will be added later.

Certain of our human embryos deserve special mention.

The youngest specimen we have furnished Series 825. The embryo is in a good state of preservation and is in the stagejustbeforetheformationofthemedullaryplate. The chorionicvesiclewas received intact,and measured without thevili7by8byII.5millimeters. A descriptionofthis embryo for publication has been undertaken by Dr. F. T. Lewis. ItistheyoungeststagewhichIpersonallyhave ever had the opportunity of examining, and it belongs among the half dozen youngest human embryos known.

A fineembryooffourmillimetershasfurnishedSeries817. It was preserved in formalin and exhibits good karyoki- neticfigures. Sofarastheconditionoftheembryoitself indicates, the specimen is normal, but it differs in many respectsfromthefewhuman embryosofthissizewhichhave been hitherto described. The anterior neuropore is wide open, and the caudal end of the spinal cord is stil in the stageofthemedullaryplate. Itshowsverystrikingpecu- liarities, by which it differs from the other human embryos ofthissizewhichhaveheretoforebeenstudied. Theques- tion arises whether this embryo is really not more normal thantheothers. Itwillformthesubjectofamonographby Dr.J.L Bremer. He hasjustcompletedwax platerecon- structionsofalthemore important parts.

The following five embryos are al normal specimens in first-class condition, which have yielded exceptionally fine series:

Embryoof8 mm. Series817. I2 8i6. I3.6 839. 23 i8i. 22.8 737-

The two embryos last mentioned represent the stage at the endofabouttwomonths. Seriesi8iconsistsofsagittal sectionsandSeries737offrontalsections. Thebrainofthis lastisbeinginvestigatedbyDr.EwingTaylor. Itisoneof the finest embryonic mammalian brains which I have ever seen, so far as the perfection of its preservation goes and the clearness with which the various parts have been differentiated bythestain,inthiscaseboraxcarmineand Lyon'sblue.

Another embryo also good, but not quite in perfect con- dition,measured IO.2millimeters,andnowexistsinsagittal sectionsasSeries736.

-Insert embryo table here-

LIST OF PUBLISHED RESEARCHES. (Based wholly or in part on material in the H1arvard.Emnbryological Collection.) 1895. F.Dexter. EinBeitragzurMorphologiedesverlangertenMarkes beim Kaninchen. Arch. Anat. Entwickelungsges, 1895, 423- 437. 1896. C.S.Minot. Theoriginaltypeofvertebratedevelopment. Procs British Assoc. Adv. Sci., I896. 1S97. A. Schaper. D)iefriuhesten I)ifferenzirungsvorghnge im Central] nervensystem und die Entwickelung der Neuroblasten und Sponigioblasten. Archiv. fuirEntwickelungsmechamk, v,31- 132. I898. C.S.Minot. Cephalichomologies. Amer.Nat.,xXXi,927-943; alsotranslatedinArch Zool.Expt.,Ser.i,Tomev,417-436. On the veins of the Wolffian body in the pig. Proc. BostonSoc.Nat Hist.,xxviii,265-274. A. Schaper. The finer structure of the selachian cerebellum. Journ. Comp. Neuirol.,vi,1-20. 8g9.A.Schaper. ZurMorphologiedesKleinhirns. Verhandl.Anat. Ges. Tiubigen,xi,I02-115. ZurHistologiedesKleinhirnsderPetromyzonten Anat. Anz., xvi, 439-446. F.Dexter. UberdieMlorphologiedesVerdaunngssystembeider Katze. Arch.Anat.Entwickelungsges,1899,I59-I92. i9oo. C.S.Minot. Onahithertounrecognizedformofbloodcirculation withoutcapillariesintheorgansofvertebrates. Proc.Boston S.N. I.,xix,I85-215. - - Onthesolidstageofthelargeintestineinthechick. Journ.BostonSoc.Med Sci.,iv,IS3-I64. Ueber mesotheliale Zotten der Allantois bei Schweinsem- bryonen. Anat.Anz.,xviii,127-136. F. Dexter. Additional observations on the morphology of the digestivetractofthecat. Journ.BostonSoc.Med.Sci.,iv,205- 212. I90I. C. S. Minot. The embryological basis of pathology. Science, xi,481-498;alsoBostonMed. Surg.Journ.,clxiv,295-305. R.T.Atkinson. Theearlydevelopmentofthecirculationinthe suprarenaloftherabbit. Anat.Anz.,xix,6io. 1902. C. S. Minot. On the morphology of the pineal region. Amer. Journ. ofAnatomy, i,8i-98. F.A.Woods. OriginandmigrationofthegermcellsinAcan- thias. Amer.Journ.Anat.,i,307-320. J.I,.Bremer. Ontheoriginofthepulmonaryarteriesinmammals. Amer. Journ. ofAnat., i,137-144. A.C.Eycleshymer. Nuclearchangesinthestriatedmusclecellof necturus. Anat.Anzx,xxi,379-385.

I902. 1903. 1904. 1i905. MINOT. F.T.Lewis. Thedevelopmentofthevenacavainferior. Amer. Journ. Anat., i, 229-244. F. Dexter. The development of the paraphysis in the comtm-on fowl. Anmer.Journ.Anat.,i,13-24 On thevitellineveinofthecat. Amer. Journ.Anat,i,26t- 267- C. S. Minot. A laboratory text-book of embryology. Svo. pp. 380. Philadelphia. J.L.Bremner. Developmentofthelungintheolpossum. Amer. Journ. Anat.,i,67-73. F.T.Lewis. Thegrossanatomiiyofatwelvemnillimeterpig embryo. Amer.Journ.Anat.,i,211-226. A. C. Eycleshymer. Notes on the histogenesis of the striated muscleinnecturus. Amer.Jour-n.ofAnat.,i,pp.xiv-xv. A.C.Eycleshymer. Thecytoplastmiicaridnuclea-chiangesinthe striatedmusclecellofnecturus. Amner.Journi.Anat.,i,285-310. F.T.Lewis. Thequestionofsinusoids. Anat.Ariz.,xxv,26i- 279. C.S.Minot. Geneticinterpretatiotnsinthedomain ofanatomy. Amer. Journ. Anat., iv, 243-263. C.S.Minot. Theimplantationofthehuman ovuimintheuterus. Trans. Amer. Gynecol. Soc., 1904, 39s-402. W. A. Locy. On a newly recognized nerve connected with the fore-braininselachians. Anat.Anzeiger,xxvi,33-63,I1I-123. RESEARCHES IN PROGRESS. C.S.MinotandE.Taylor. Normalplatesofthedevelopmentof the rabbit. Part V. of Keibel's series of "Normentafeln" (in press). C. S. Minot. Early development of the human chorion and decidua. F.T.Lewis. Developmentofthelymphaticsinmammals. Descriptionofa veryearlyhuman embryo. J.L.Bremer. Anatomyofahumanembryooffourmillimeters. E.Taylor. Structureofthehumanbraininthetvomonths' embryo. C.F.W.McClure. Developmentoftheveinsintheopossum. (Intarton our material.) Edw.Fawcett. Developmentofthefacialbonesinman. (Inpart on our material.) JohnWarren. Developmentofthepinealregioninnecturus.

VOL. XIII. PLATE XXXIX. (3 figures)