Book - A History of Embryology 1959-2

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Needham J. A History of Embryology. (1959) Cambridge University Press, London.

1959 Needham: Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4

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This historic 1959 embryology textbook by Needham was designed as an overview of embryology history. Currently only the text has been made available online, figures will be added at a later date. My thanks to the Internet Archive for making the original scanned book available. History Links: Historic Embryology Papers | Historic Embryology Textbooks | Embryologists | Historic Vignette | Historic Periods | Historic Terminology | Human Embryo Collections | Carnegie Contributions | 17-18th C Anatomies | Embryology Models | Category:Historic Embryology Historic Papers: 1800's | 1900's | 1910's | 1920's | 1930's | 1940's | 1950's | 1960's | 1970's | 1980's

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Chapter 2

EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

x. Patristic Speculation

We are now at the beginning of the second century AD. The next thousand years can be passed over in as short a time as it has taken to describe the embryology of Galen alone. The Patristic writers, who on the whole were careful to base their psychology on the physiology of the ancients, had little to say about the developing embryo. Most of their interest in it was, as would naturally be expected, theological; Tertul- lian,‘ for instance, held that the soul was present hilly in the embryo throughout its intra-uterine life, thus denying that kind of psychological recapitulation which had been suggested by Aristotle. “Reply," he says in his De Anima. ‘'0 ye Mothers, and say whether you do not feel the movements of the child within you. How then can it have no soul P” These views were not held by other Fathers, of whom St Augustine of Hippo (De Immartalitate et de Quantitate Animae) may serve as a repre- sentative, for he thought that the embryo was “besouled" in the second month and “besexed” in the fourth. These various opinions were duly reflected in the law. and abortion. which had even been recommended theoretically by Plato and defended practically by Lysias' in the fourth or fifth century B.C., now became equivalent to homicide and punishable by death. This fact leads Singer and Jones to the view that the Hippo- cratic oath is late, perhaps early Christian. The late Roman law, which.

according to Spangenberg,' regarded the foetus as not Homo, not even

Infant. but only a Spa: animanlis, was gradually replaced by a stern

condemnation of all pre-natal infanticide. “And we pay no attention,"

said the Bishops of the Quinisext Council. held at Byzantium in 69:,

‘ Qbskuetionixt orglnicisrn can count Tertullinn on its side. Writing in 5.17. zoo he_nrd'. "flgrophilus, the physician, or rather butcher, dissected Gm: persons that he might ucrutmlse nature; he hated man that he might gain knowledge. I know not whether he explored clearly all the internal art: of man. for death change: them from their state when alive, and death in his ds was not simply death, but led to error/mu the very from: 0/ cutting up."

' On the Itlms o abortion in Classuml Greece, 5:: Moisxidea.

' Consult elm Goeckel and Moruehe.

75 A HISTORY OF IIMBRYOLOGY

"to the subtle distinction as to \\ eth '

formed." Other authorities. followiiig S‘t::\‘1i:11sft°x'ix‘:sto1:lrf‘::x-fnxnltiiletlixluunl “kw, and the canon law as finally crystallised rieoogniscd first cg: fortieth day for males and the eightieth day for females as the momm: of animation.‘ but later the fortieth day for both sexes. The ernbryo rnfannam: thus had no soul, the rmbryofarmazux had, and as a corollary could be baptised. St Thomas Aquinas was of opinion that embryos dying in Merv might possibly be saved: but Fulgentius denied it.‘ As for the ancient belief that male embryos were formed twice as quickly 33 {Emile Oncs. it lingered on until Goeliclre took the trouble to disprove it experimentally i.n 1723.

Clement of Alexandria, in his book lrfyo; Jrearguzww‘; .196; "E}.1rpro;, has some remarks to make on embryology, bu: add; naming to the knowledge previously gained. He adapts the Peripatetic view that generation results from the combination of semen with menstrual blood. and he uses the Aristotelian illustration of rennet coagulating milk. Lactantius of Nicomedia, who lived about the date of the Nicene Council (LI). 325), perpetuated the deeply rooted association of male with right and female with left in his book On the Work of God, De opificia D35. He also maintained that the head was formed before the heart in ernbryngeny. and seems to have opened hen's eggs systemati- cally at dilferent stages, so that to this extent he was a betterembryologist than Galen.

The inherent formative power of the egg has been translated by biologists of every period into the language of their time. Just as Dricseh sought to acclirnatise it to the unfavourable environment of :1 post- Cartesizin world, so St Gregory of Nyssa, about AD. 37o, clothed it in Patristic terminology, and produced a theological variety of neo-vital- ism. His most important hiologiul works, the .-reg) mzraozsurig é)‘eQ(xI):l'O1J, On the Ilfakiug of Man and .-zegl '{‘"2'l:, On 1/1: Soul. con- tained such passages as these:

The thing so implanted by the male in the female is fashioned into the different varietiu of limbs and interior organs, not by the importation of any other power from without, but by the power which resides in it transforming it.

And elsewhere:

For just as a man when perfectly developed has a soul of 2 specific nature. so at the fount and origin of his life he shows it) himself thnteranfonnatxm of soul which is suitable for his need in preparing for itself its peculiarly fit

‘ See the discussion of Cleopatra (p. 65). ‘De I-‘nit, ch. 2'). See Co-ulton, and p. 205 belowr

76 IIMBRYOLOGY FROM GALEN TO THE RENAISSANCE

dwelling-place by means of the matter implanted in the maternal body; for we do not suppose it possible that the soul is adapted to -a strange building, any more than it is possible that a certain seal should agree with a different impression made in wax.

Thus the soul makes its body as if it were a gem making a stamp upon some soft substance, and acting during development from within. “No unsouled thing," says Gregory, “has the power to move and grow.”

Late Latin writers, other than the theologians, do not say much about it. There is a passage in Ausonius, however, which describes the development of the foetus (Erlag. :12 Rat. }>uerp.), but it is almost wholly astrological. Elsewhere he says:

juris idem tnlius est, quod ter tribus; omnia in istis; for-rna hominis cocpti, plenique exactio partu, quique novem novies fati tenet ultima finis.‘ Idyll 11 (Gryphus ternarii nurneri), 4-6.

But this is probably a late echo of the Pythagoreans rather than an early prelude to Leonardo da Vinci and the mathematisation of nature.

2. Contributions of Jewish Thinkers

That great mass of Jewish writings known as the Talmud, which grew up between the second and sixth centuries A.D., also contains some references to embryology, and certain Jewish physicians, such as Samuel ha-Yehudi, of the second century, are said to have devoted special attention to it. The embryo was called pzri habbetgen (fruit of the body), ]b:71 ‘fin. It grew through various definite stages:

(1) golnn (fonnless, rolled-up thing), aha, o—r.5 months.

(2) slujir mmtgqém (embroidered foetus), upfib T917.

(3) 'uHmr (something carried), 1:131, 1.5-4 months.

(4) walad (child), 1'71, 4-7 months.

(5) walad J‘/rel gnyzinui (viable child), my"? '21: 1'71, 7-9 months.

(6) ben she-kallu khadfixhaw (child whose months have been com- plctcd). r-mn 1'::v 1:.

The ideas of the Talmudic writers on the life led by the embryo in utera are well represented by the remark, “It floateth like a nutshell on the waters and moveth hither and thither at every touch".

tmt cm W ‘arm: rum ruxh um um: .-um 151 no‘? ‘mm: ~:n -mm .1x:‘n [N35 vpw 3-'72 1x7:3N p-n:

"fine power of 3, in 3 times 3 lie: too, 4 Thu: 9 rules human form Ind human birth. And 9 times g the end othuman ms.

77 A I-HSTORY or EMERYOLOGY And the classical passage,‘

Rabbi Simlai lectured: the babe in its mother‘: womb is like a rolled-up fcfllzll. W_l!h folded arms lying c.lo:ely‘pressed together, its elbows resting on

3 ips,.Its heels against its buttocks, its head between its knees. Its mouth is

osed, its navel open. It eats its mother s food and tips its mother’: drink: but it doth not excrete for fear of hurting.

‘zrr 1'1‘ nnm Hove: uprn‘: inn 3:2: man ‘I'm rm‘; *i<'7m ‘:1’! m7

rm» mt-n T'n'IJJ.V ': ‘av rapy ':n rnuzwx ': '7» i~‘>~xx me has ‘n:

1mm .-mu nmtn n‘7:m mm .-mp ‘mm mm: mam mno T‘D'l1‘J'1Zl r: 1': am: mm-m~ new term irmnrur

It was thought. moreover, that the bones and tendons, the nails, the marrow in the head and the white of the eye, were derived from the father, "who sows the white,” but the skin, flesh, blood, hair, and the dark part of the eye from the mother, "viho sows the red.” This is evidently in direct descent from Aristotle through Galen, and may be compared with the following passage’ from the latter writer's Com-

mentary on Hippacmttx:

We teach that some parts of the body are formed from the semen and the flesh alone from blood. But because the amount of semen which is injected into the uterus is small, growth and increment must come for the most part

from the blood.

It might thus appear that, just as the Jews of Alexandria were readhig Aristotle in the third century B.C., and incorporating him into the Wisdom Literature,‘ so those of the third century A.D. were reading Galen and incorporating him into the Talmud. As for God, he con- tributed the life, the soul, the expression of the face. and the functions of the different parts. This participation of three factors in generation—— male, female, and God——is exceedingly ancient. 25 IMY be I534 in Robertson-Smith, Some Talmudic writers held that development began with the head, agreeing with Lactantius, and others_ that it began at an nave], agfeeing with Alcmaeon. Weber has given an

‘ Nldd. 3a b. , . . .

1 Ten centuries later it was still wenhwhile tn: Hm-ey to line x hit it this opinion. “In the interim,” he Hay; 0653. p. H6). "we annot chiuelaut uni]: I; tlut fond Ind lietitiou: Division of the Pam, mm spenmucal end sangumrous. -5 I my P!"._‘;‘L\’,$ rmmediztely framed or the semen, end _were not _xll of one an-net nndyrisld Anthropology may throw light on the ulumnte Oflglfl of mm: of thesedtsrnoug I :5: Thus Mr Batcsnn inform: me that the natives ofNew‘Gui.neI flnkgdlrd H tween [he no flesh provided by the mother. Ind oi: whiz: ban: prpvr f 1:»; amend: They mi hxrdly rim learned this from Gnlen. Similarly. the nauvu o u.

ing (0 Pavtdermaltrr, hold the j‘Ariazotelian" view that the memrrunl blood 1'-I I138 material from which the foetus is (armed. ' See p. 64. 78 EMERYOLOGY FROM GALEN TO THE RENAISSANCE

account of the Talmudic beliefs about the infusion of the soul into the embryo.1 They do not seem to have embodied any new or striking idea.

Although the Talmud contained certain references of embryological

interest, the first Hebrew treatise on biology was not composed till the tenth century, when Asaph Judaeus or Asaph ha-Yehudi wrote on em- bryology about A.D. 950. His MSS. are exceedingly rare, but. according to the descriptions of Gottheil, Steinschneider, Simon and Venetianer, they contain several sections on embryonic life. For further details on the whole subject of Jewish embryology, see Macht, and especially Preuss. As is well known, the general view of the world in the Kahbalab. is that of the emanation doctrines of neo-Platonism. The world is full of Ideas or Daemons which are the spiritual representatives of all living things. A thing has life if it works according to certain aims. Living things are nizzuzalh (sparks): a conception which may be connected with the symlerelix of the medincval rnysdcal authors such as Dionysius the Pseudo-areopagite. But according to the emanation theory these sparks are not simply situated in the world side by side. They are contained (inserted, eingmhachtelt) in other things, which can again split into endless other sparks (manads). In this sense all men are contained in the body of Adam Protoplastes, and the human frame is the microcosm or imitation in little of the macrocosm. Both can be divided into an infinite number of parts or limbs, each having a spiritual representative. which is evidently identical with the archaeus insiius ofvan Helrnont. But the spiritual representative does not enter the body from outside. It builds the body by splitting itself into an infinite number of new limbs or sparks, and in this monistic View of matter and spirit there are all stage: from the non-corporeal through the finest corporeal essence to the grossest materials (the ladder of emanations). Such a view occurs in Leibniz‘ (see Feilchenfeld and Cassiret“) and Spinoza as well as van Helmont, but was of course contrary to that of Dacartes and Stahl. In the Kabbalah Denudata there is no embryology as such.‘ The Sefer Yesirah or Book of Creation, translated into German by Lazarus Gold- schmidt, does contain embryological ideas, but they are only mystical

1]x2dz2ix:Ixe Tlwologie, p. :15.

' In Leibniz’ thought "each part of the organism an be considered Is a garden of plants or I whole pond of fishes, but even each branch, each limb. of the organism. each drop ofits fluldl, IS itselfsueh . pond or garden." Here and in similar passages or van Helmont there Ire important S! cm of the histary at’ the concept of the relation between the whalelnd its parts in bio ogy and pathology. Life is the process of develop- ment of certain preformed things, and each monad rninorl all the others like the nodes of Indra‘: Net. There can be little doubt that Leibniz was influenced consider- -bly by neo-Confucian md Buddhist idea: (ct. Stink: and C1t1'l£ta!wn in China,

vol. 1. pp. 496 11.). ' Pp. 46, “:5. ‘ Cf, Vol. 2, pt. n, tnmre xxx. Pheum. 2.

79 A HISTORY OF EMBRYOLOGY

and allegorical pictures of the work of creation, without scientific value.

But from the Kabbalistic ideas already mentioned there resulted a speculative embryology dominated by the suggestion of a general pre- formationisrn. The monad of Leibniz has no windows. The Kah- balah stresses the differences between individual person: rather than their likeness. Their fate, talents, personal gifts, etc., are determined according to the virtues of the parents and their thoughts in the moment of conoeptiom The nature of the soul determines the sex. The individual personality is marked by the pztrticular name which is bestowed upon the soul in heaven before the creation of the body. For the development of the human body itself thert: is required (as in van Helmont's view) the seed, a portion of matter with a spiritual Archaeus, the aura r.-ilalzzs, in it, corresponding to the Afistutfilnian anifia Etgelzgfa. The worl: is full of such seeds, because all 1 ' gs, in U 1“: ‘ 33565, We 1 9“ existence to development from seeds‘ As the classitzl examples of diseases in the writings of Paracelsus and van Helrnont arethe plague and other infections, the seeds were prohably thought of much as.our micro-organisms are. Imagination_of adldisgiasse lea;_:ls to _l‘t:C0n!l'8t31€t:1g.

he Archaeus of the bod eneratmg e ease mm 1 P1'5‘‘’-’‘’-5 ‘ i==d- A“ is <23; ‘ ' ' ' ' e mi e term 6:

1‘:/Zflgin ::::si,ol::£lgd;l:l1}: i,ogos, God‘; .5011, or Christ, who is the

mum zxemplanir at fannalis, the representative oi Gods sgazlenrflg In °“°“,““‘“3 ”§§f§§1:cr'Lar;§§ the a or yennat as 0 e . . ’ ’ , ,. theorygin embryology‘ and the ..¥,3¢;tenology’ of Atlmnasrus Istrcher;,x

But the Matter and the aura malt: alone are not stfilficilirjrti to ccrlea : “T5, in spin of the facg am gheyean develop parts of I e Y sul :’ molar, or the whole bad)’ 35 i" mnbom ",1fams' Th: "mm 1-07” citalz, an entity of the suhtles! corpomltff =*"d_8’;*%§i”“t’V;S mg light, immediately prooeedmg from God, ts require 1] bi:/h.min beginning ofli{e—Lhe Hebrew 07, ‘mt, means light alsawe . as] kgeld mad-

Au this spend-nive =mbryo1°sv has been s°.*"°“' ‘ ‘-""3." vielw of should make us hesitate, as w._Pagcl says In a°°€I_""‘Ed If ‘ha db Bilikiewicz that the Baroque pcrlod “VS W_11°llY i'l‘°}‘lunate _y_ " velvpinz; mechanism °‘ D°‘‘=’‘“‘-‘': “‘ “l““°“ ‘° llgmll-“ytlIuClv::l>‘rk1(i7(l' to one development of exmiardtrutry interest, name) [3, . Mm Marcus Marci ofKrunL1nd, a B0h°"1“m~ H35 I‘I',”’"',';iop"a‘ 71mm H;

‘m  W 3  °‘ —‘“:“;;o:l;?:.,:;m,,.

optics (see Hoppe; R°5=!1f¢ld): and SPCC“ “W”

. . ‘ { .1, I I For Iurther dismssion of prrformzuonxsm ma «an, see p 66 o = P"==“ work. 230 EMBRYOLOGY FROM GAL!-IN TO THE RENAISSANCE

ology. Thus he explained the production of manifold complexity from the seed in generation by an analogy with lenses. which will produce complicated beams from a simple light-source. The formative force radi- ates from the geometrical centre of the foetal body, creating complexity but losing nothing of its own power. Monsters originate from accidental doubling of the radiating centre, or from abnormal reflections or re- fractions at the periphery (cf. mirror-image rerluplications, accessory organisers, :r'!us incm-us oixmum, etc.).

Marcus Marci thus links together the following trends of thought: (r) the old Aristotelian theory of seed and blood, (2) the new rationalistic mathematical attitude to generation as e.g. in Gassendi and Descartes. (3) the new experimental approach, in his contributions to optics, (4) the cahbalistic mysticism of light as the fountain and origin of things. Finally (5) by his brilliant guess of centres of radiant energy, he antici- pates much of modem embryology (field theories, fate of part as func- tion of position, etc.). Pagel and Baumann give an elaborate discus- sion of his opinions.

The only parallel to this occurs, it seems, in a quarter far removed from Marci at Prague, but equally devoid of influence on contempo- raries, namely the D: Malu Animalium of Borelli, the founder of the iatro-mathematical school (p. 153). Chiarugi gives an account of the chapter on generation.‘ Its interest is that Borelli compares the semen to a magnet arranging iron particles in a field of force. There is really little difference between this conception and the "individuation field" of modern ernbryologirsts. In Harvey, too, a reference to the magnetic field can he found. In the discourse on Conception (1653, p. 539) he says:

The Woman or Female doth seem, after the spermatical contact in coition, to be affected in the same manner, and to be rendered prolifical, by no sen- sible corporezl Agent; as the Iron touched by the Loadstone is presently in- dowed with the virtue of the Loadstone, and doth draw other imn-bodies onto it.

In the eighteenth century, of course, traces of this are easier to find. Thus from Bourguet, one of the saner ovistic prefomiationists (see p. 207), may be quoted (1789):

Le Méchanisme Organique [which works in generation] n’est autrc chose que la Comhinaison du Mouvement d‘une infinite de Molecules éthériennes, nériennes, aqueuses, oléagineuses. salines. terrestres, etc.. accommodées in des systémcs particuliers, determines dis le oommencement par la Sagesse

1 Pt. 1! ch. 14, in vol. 2, pp. 378 ff. ms.-6 81 A HISTORY OF EMBRYOLOGY

Iuprrime et unis chacun 3 une Aetivité nu Monad ' lie; 5 '

I %c]l%d(t”l.\‘ mlinrt JIEVII ton lyxtlnrz rant rubcofilogluniefflet mmnmn’ . e I eas o arsons X752) are also rel t- th ‘11 be { (3

discussed on p. 192 belos , mm ' Cy W‘ cm

3. Embryology among the Arabs

Arabic science, so justly famed for its successes in certain fields such as uptiu and astronomy, was not of great help to embryology. My friend Profmsar Reuben Levy has collected for me the following emlnryov logrml excerpts from the Koran:

nxnr (12 ii.) We created man of a choice extract of clay, then we placed him as semen in I sure place, then we created (2) the semen into dotted blood, then we formed the dotted blood into a marsel offlesh, then we created the rnmsel into bones, and we covered the bones with flesh, then we produced out of it a new creature. mi (44) God created every beast out of water. xxxv (I2) Godcreatedycu frornmrth,thenfmma clot, thenhcmadeyuu pairs. um! (36) Does man think that he shall be neglected? (37) Was he not a clot of emitted seed? (38) Then he rm: congealed blood, then God created him and fashioned him. (39) And made of him the pair, male and female. gxxvx (3) Vgrny, we created man from a do: ofmixtum.

A seventbcentury echo of Aristotle and the /iyur-ceda.

Thetxeatises ofthe Brethren of Sincerity (Ra:¢i’r'lIklma‘n al-Sufi’), an ammymaus gmupwho wished to popularise science in the late tenth cen- tury at Basra in Iraq, contain afew references to generation, again Aristo- tdian, mgmiauing the cheese analogy, but mostly astrologiml. Abfi’l- Hasan ‘Ali ilm Sahi ibn Rabhan al-Tabari, a Musllm physician who flourished under the Caliphate of al-Mutawairkil about ILD. 850, wrote 3 book gflgd 71;; Paradise of Wirdom, in which an entire _part was devoted to embryology, all the more interesting as It is a‘mrxture of Greek and ancient Indian knowledge. Browne give; a dcscn_puon of In Ilm Rahhan's contemporary, Thibit ibn Qurra, |s.also_sa:d. to have written on embryology. The great Avicenna, or. I0 EIVC l}1m his PWP" name, Aha ‘Ali al-Hasan ibn 'Al)El:tll§l1 ibn Sini, who lived from 98o to 11:37, devoted certain chapters of his Canon Meaitcinae to the dc- velapment of the foetus. but fldded nothing to §3a1=n- Hts C°“_‘=mP°f:3' rim, Aha’!-Qisim Maslarna ibn Ahrmd al-Majflfi anfl ‘Arib ibn Sn rd nl-Kfitib, a Spanish Muslim, wrote treatises on the generation 0‘ animals, but neither has survived. A

I rum: mine. I an indebted to my friend Dr W. Page! far most of the fwresmnx

infmsnnum concerning the Klbbzhh. 8:-. EMBRYOLDGY mom GALEN TO THE RENAISSANCE 4. Alchemy and Embryology

What was alchemy doing all this time? It was engaged on many curious pumxits, but among them the interpretation of embryonic de- velopment was not one. Alchernical texts before the tenth century do make reference to eggs from time to time, but it is safe to say never with any trace of an interest in the development of the embryo out of them (cf. Berthelofs collection‘). It is not until after the time of Paracelsus that the notion of applying chemical methods to eggs or embryos arises at all.

Although somewhat out of chronological order, a word may be said here oonoeming Par-aoelsus. Though deserving of little remark by the embryolcgist. his recipe for making a homunculus cannot be passed over. It occurs in his Treatixe ea1rcem1'ng the Nature of Things, Book 1, concerning the generation of natural things, p. 124.. Human semen is allowed to putrefy in a cucurbite for forty days "with the highest putrc- faction of the vemrr eyuinus" till it moves and is agitated; it is then fed cautiously and prudently with the areanurn of human blood for forty weeks. The neuter equinu: may have meant an apparatus for maintaining a temperature of about blood heat by the use of fermenting horse-dung. Paraoelsus also wrote a Librr 11': generutione horninir which only exists in fragmentary form. His view that “putrefaction is the first initiative of generation" (p. 12o) may stand in some relation with the cheese analogy.‘

It is of interest that this doctrine is embedded in the Hebrew Liturgy (p. rgo), where in chapter 3 of the Ethics of the Father: we find

Aqabyzi, the son of Mahalalel, said, reflect upon three things . . . whence thou earnest, whither thou art going, and before whom thou will in future have to give account and reckoning. Whenoe thou carnest—from a putre/ying drop (nmuo noon rm: rim), etc., etc.

The date of Aboth is uncertain; it is first cited by name in A.n. 299 but is certainly much older (30 B.C.—A.D. no). The particular author in question here, Aqabya hen Mahalalel, was one of the earliest Tannaim (Rabbis of the Mishnah), since he has no title, probably a contemporary of Hillel, and therefore about the end of the first century 13.0. The doc- trine of generation implying putrefaction is doubtless connected with the doctrine of spontaneous generation, the history of which has been so well written by van Lippmann, but the origin of both is still very obscure.

‘E.g. vol. 2, pp. 56 ff. , I Pp. so, 85 of the present book; lee Ilsa Cole, p. I.

83 A rusrotur or EMBRYOLOGY

5. The Visions of St Hildegard

Not long after the death of Avicenna, St Hildegatd was born. She lived from xo98 to 118?, and was ahbess successively of Disibodenberg and Bmgen in the Rhmeland. Her treatises on the world, which are an extraordinary medley of theclogiml, mystical, scientific and philo- sophical speculation, have been brilliantly described by Singer, and though in her lroolta, Liter Sa'n'a: and libzr Ditinorum Operwn simplicis hmmms, there 35 little of emhryological interest, yet she does give an account of development and especially of the entry of the soul into the foetus.‘

This is seen in an illustration (Plate IV, opposite) from the Wies- baden Codex B of the Liber Sciviax. The soul is here shown passing down from heaven into the body of the pregnant woman and so to the embryo within her. The divine wisdom is represented by a square object with its angles pointing to the four corners of the earth in symbol of stability. From it a long tube-like process dsoends into the mother's womb and down it the soul passes as a bright object, “sphen'ml" or “shapeless," illuminating the whole body. The scene shows the mother in the foreground lying down; inside her there are traces of the foetal membranes; behind this ten persons are grouped, each mrrying a vessel, into one of which a fiend pours some noxious substance from the

left-hand corner. St Hildcgard describes and expounds the scene as follows?

Behold, I saw upon mrth men carrying milk in earthen vessels and making cheeses therefrom. Some was of the thick kind from which firm cheese is made, some of the thinner sort from which more porous cheese is made, and same was mixed with corruption and of the sort from which bitter cheese is made. And Isarv the likeness of a woman having a complete human form within her womb. And then by a secret disposition of the most high crafts- man, a fiery sphere having none of the lineaments of a human body powtssed the heart of the form and readied the brain and transfused itself through all the members. . . . And I saw that many circling eddies possessed the sphere and brought it earthward. but with ever-renewed forte it returned upward’: and trailed aloud, asking, "I, wanderer that I am, where am I?" "In death a shadow." “And where go I?” "In the way of sinners.” "And what is my hope?“ “That oi allwandertn.” . . . As ior \hu‘sewhnmthno.hmtseenua:ry- ing milk in earthen vessels, they are in the “mid, men and women alike, having in their bodies the seed of mankind from which are pmaeated the various kinds of human. beings. Part is thickened heuuse the seed In its

- ' in nu have been 1-rnflnx 1.; i:3.’.§‘.‘Z“£”§.‘2‘;r§”;,”°.‘:i‘.i’i :";ir“ft.2".'f.E:’f;E.§°5{?‘2r§?.mb.y’I. (see Uebcrwrzk Pnechtzr, p. 393) On her pathology, wee Schulz. Cf. Ltebeschutx. pp. 65 ii. - Trlmlntion by singer. 84 PLATE IV

An ilhulrazianjmm the Libcr Scnias 0/ SI Hthizgnrd 9/ Bmgen (Wznbadzn Code: B), .t/Intcmg I71: dertznl n] (/15 um! {um 1/1: embrga (c. ,.m n5u) (n/In Clzarln Singer).

Sal EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

strength is well and truly concocted and this produces forceful men to whom are allotted gifts, both spiritual and carnal. . . . And some had cheeses less firmly curdled, for in their feebleness they have seed imperfectly tempered and they raise ofispring mostly stupid, feehle and useless. . . . And some was mixed with corruption . . . for the seed in that brew cannot be rightly raised, it is invalid, and makes misshapen men who are bitter distressed and op- pressed of bean so that they may not lift their gaze to higher things. . . . And often in forgetfulness of God and by the mocking devil a mistia is made of the man and the woman and the thing born therefrom is deformed, for parents who have sinned against me return to me crucified in their children.

We have already traced the wanderings of the cheese-analogy, which, beginning fresh with Aristotle, was taken to Alexandria, incorporated itself in the Wisdom Literature, and so found its way to the Arabic of ‘Ali ibn al-‘Abbas al-Majfisi, or Haly-Abbas, as he was known in the ‘Nat, a Persian.‘ His Liber T otiur appeared in Latin in 1523, but had been translated much earlier, at Monte Cassino between‘ 1o7o and r085. by Constantine the African, who called itL1'ber :12 Hunmrm Ndtura, and gave it out to be his own work. Thus St Hildegard obtained it, and worked it up into one of her visions. At this point embryology touched, perhaps, its low-water mark. But a great man was at hand, destined to carry on the Aristotelian tradition and to add to it much of originality, the Dominican Albertus of Cologne. Before speaking of him, however, a word must be said about that very queer character Michael Scot (1 178-1234), who, according to Gunther,‘ “appeared in Oxford in 1230 and experimented with the artificial incubation of eggs, having got an Egyptian to teach him how to incubate ostrich eggs by the heat of the Apuliart sun." That “muddle-headed old magician,” as Singer severely calls him, was not the man to profit by it, but the point is interesting, especially as an Egyptian is mentioned. Haskins, in his curious studies of the scientific atmosphere of the court of the Emperor Frederick II of Sicily, has shown Scot, newly arrived from his alchemical studies in Spain, assisting that learned and unoi-thodox monarch in his artificial incubation experiments.

One should remember that about the same time as Hildegard, some progress was being made in gynaecology and obstetrics at the School of Salerno (cf. Bayon, 1940). A not uncommon mediaeval manuscript, De Parrionibur llfulimnn, is usually ascribed to Trotula of Salerno, a matron (cf. Hurd-Mead, 1930). It recommends support of the peri- naeum inchildbirth and primary suture of lacerations. The text contains

‘H‘ "Li! M ' rm three 1: " fth Es

,oneo e greatestp yueunso e . tern

‘Vol 3, p. 151. 85 A ms-roar or EMBRYOLOGY

many references to Muslim and Hebrew physicians epealu I

drugs from Arabic pharrnacopoeias, and avoids’ magicaol There is in tradition that the “mulieres Salernitanae" taught obstetrics there, and the name of one woman professor from sornewlnt later at Nnplee has come down to us, Costanza Calenda of Salerno, who leg. tured at some period between 1326 and 138:.

6. Alberto: Magnus; the Remwalrenlng of Scientific Embryology

Albertus Mognus of Cologne and Bollstadt was born in rzo6, and died in 1280, six years after his favourite disciple, St Thomas Aquinas. The greater part of his life was spent in study and teaching in one or other of the houses of the Dominican friars, to which he belonged, though for o ti.me he was Bishop of Regeruburg. Albert resembles Aristotle in many points, but principally bemuse he produced biological worlt with, as it were, no antecedents. Just as Aristotle‘: contributions to embryology were preceded by no more than the diffuse speculation: of the Ionian nature-philosophers. eo Albert’: came imtnedintely after the dead period represented by the visions of St Hildegard. In many wayu, Albert’: position was much less conducive to good work than Aristotle's.

Albert follow: Aristotle closely throughout his biological writings,‘

quoting hirn word for word in large amounts, but the significant thing ’

is that he does not follow him slavishly. He mernbled Aristotle in paying much attention to the phenomena of generation. as n rough computation shows; Aristotle devoting 37 per Cmh of hi! l7l0l°Ell=l writings to this subject, and Albert 3r per cent-. 10 \VlI3¢h Gale!“ 7 per cent. may with interest be compared Albert is urtremely inferior to Aristotle. however, in point of arrangement, for Aristotle, ulthough some of his books, euch as the De Generation: Am'mol:'ur_n, are supi- ciently confused and repetitive, does yet eucoeed in infuerns I °l"'"_}' and incisivenese into his style. Albert, on the other hand, tllowe his argument to wander through his twenty-six books De Ammalnbrrr tn the most complex convolutions, so that the sections on _generation and embryology are found indiscriminately in the first. sixth. ninth. 55' teenth. sixteenth and seventeenth. In Book [he gives nkmdpf lurnm_afy or skeleton of his views on the embryo. These l_'allow Aristotle ‘Nil’ closely; thus he accepts the Aristotelian dessificatxon of record- ing to their mxnner of generation, and thanks mll_that caterptllfir‘-e org immature eggs: he derive: the embryo _r'rorn the white. 310! ll" 3'0 ol‘“ he explains why soft-shelled egE$-‘hem! ““?¢|'f‘°‘- ”° °f °“°_;° am only. But there are new ohservntrons; for nastanoe, he descn cox ovum in own, which he ha seem 93111“! 5‘ ' "4“"“P‘””“‘- ‘mi 1“ '9‘ ' See Bllu. 86 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

definitely of the seed of the woman, thus departing from Peripatetic opinion, and adopting the Epicurean view. The female seed, he thinks, suffers coagulation like cheese by the male seed, and to these two humidities there must be added a third, namely the menstrual blood (corresponding to the yolk in the case of the bird).

When these three humidities therefore have been brought into one place, all the similar members except the blood and {at are formed from the two humidities of which one generates actively but the other passively. But the blood which is attracted for the nutriment of the embryo is double in virtue and double in substance. For a certain part of the blood is united with the sperm in such a way that it takes on some of the virtue of the seed, because a certain part of the spermatic humour remains in it. and from this are begotten the teeth and for this reason they grow again if they are pulled out at an age near the time of sperm-making and do not grow again at an age remoter from this, at which the virtue of the first generating principle has vanished from the blood. But another part of the bloodis of twofold orthreefold substance and from the thick part of the blood itselfis generated the flesh. And this flows in and flows out and grows again if rubbed away. From the watery part of the same blood or of the nutritive humour are generated the fat and oil and this flows in and out more easily than the flesh itself, but other parts of the blood are its refuse and impurities and are not attracted to the generation of any part of the animal, but having been collected until birth are expelled with the embryo from the uterus in the foetal membranes. like the remnants in the hen’: egg after the chiclt has hatched. There is a similar virtue in the liver and heart of animals, which organs after the animals are born form the flesh and fat

from food in accordance with its twofold substance, and expel the refuse as we said before.

In the sixth book Albert contradicts Aristotle's opinion that the male chick develops out of the sharp—ended egg, and one hopes that he is going to say there is no relationship between egg-shape and sex; but no, he goes on to say that the Aristotelian statement rested on a textual error (in which he was quite wrong), so that really Aristotle agreed with Avicenna in saying that the mala always develop from the more spherical eggs because the sphere is the most perfect of figures in solid geometry. These errors had a most persistent life; Horace has a passage in which they appear—-

longa quihus facies cvis crit, illa memento ut suci melioris, et ut magi: alma rotundis poncre: nztmque marem cohibent callosa vitellurn.‘

‘ "When you would feast upon eggs, make choice of the long ma; they are whiter Ind rweeter and more nourishing than the round, for being hard they contain the yolk of the male." Book H, rat. 4, l. ta.

87 A HISTORY OF EMBRYOLOGY

They were finally abolished by two naturalists, Gfinthcr and Bible, who took the trouble to disprove theni arperlmenuuy in thc cightccmh century. Albertus refers here to artificial incubation:

For the alterative and maturative heat of the egg is in the egg itself and .5, Waflnlh the bud provides is altogcdier atcmal (txtrfnu-cu: es! nzmmi'ru‘- cularu) since in certain hot countries the eggs of [owls are put under the surface of the earth and come to completion of their own accord, as in Egypt, ibrhthe Egyptians hatch them out by placing them under dung in the sun-

ig .

Next he speaks of monsters and of the modes of corruption of eggs, which he divides into ‘four: (1) decomposition of white, (2) decomposi- tion of yolk. (3) bursting of the yolk-membrane. (4,) antiquitas cox‘.

And from the second cause it sometimes happens that in the corruption of the humours certain igneous parts are carried blazing to the shell of the egg and distribute theniselvs over it so that it shines in the dark like rotten wood; as happened in the case of that egg‘ which Avicenna said he saw in the city called Kanetrizine in the country of the Carascenes.

Albert is inclined to think that astrological influences may have an eifcct on foetal life, but he treats the suggestion with considerable scepticism, although he believes that thunder and lightning kill the embryos of fowls (a popular belief to which Féré tried not long ago to give a scientific foundation), and he regards the embryo of the crow as especi- ally susceptible, though on what grounds he does not say.

The fourth chapter of the first tmctate of the sixth book contains Albert's description of development of the chick, and is extremely interesting. He makes two principal mistakes: (a) he describes a quite non—existent fissure in the shell by which the chick may emerge, (12) he maintains that the yolk ascends after a day or two into the sharp end of the egg, adducing as the reason that there is found there more heat and fumiative force than clsewhcre. On the other hand, he correctly de- scribes (a) the pulsating drop of blood on the third day, and (12) he identifies it with the heart with its ryslolen e! dyasiolm sending out the “formative virtue" to all the parts of the growing body. He notices (c) that the difierentiaxion of the chick at first proceeds rapidly and later more slowly. But the most notable characteristic of Iilherts embryology is the way in which he is hampered by hi-9 lDffl"l“Y.‘° invent a technical terminology. Singer has studied the way in which anatomical terms, such as "syrac ." BE-. l‘am=_ 13110 1158. but “'h3'€"f’ the causes were which produced them, “KY did 11°‘ °P°““° m“°h m

I See on this subject Zieh. 88 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

Albert's mind. He represents the point beyond which embryology could not advance, until it had created a new set of terms. This is well illus- trated by the following passage:

But from the drop of blood out of which the heart is formed, there proceed

two vein-like and pulsatile passages, and there is in them a purer blood which forms the chief orpns such as the liver and lungs, and these though very small at first grow and extend at last to the outer membranes which hold the \vhole material of the egg together. There they ramify in many divisions, but the greater of them appear: on the membrane which holds the white of the egg within it [the allantois]. The albumen, at first quite white, is changed owing to the power of the vein almost to a pale yellow-green tint (paleamn tvlorern). Then the path of which we spoke proceeds to a place in which the head of the embryo is found carrying thither the virtue and purer material from which are formed the head, and the brain, which is the marrow of the head. In the formation of the head also are found the eyes and because they are of an aqueous humidity which is with dilficulty used up by the first heat they are very large, swelling out and bulging from the chic!-:'s head. A short time afterwards, however, they settle down a little and lose their swelling owing to the digestive action of the heat—and all this is brought about by the action of the formative virtue carried along the passage which is directed to the head, but before arriving there is separated and ramified by the great vein of the albumen-membrane, as may be clearly seen by anyone who break: an egg at this time and notes the head appearing in the wet part of the egg and at the top of the other members. For what appears first in the making of a foetus are the upper parts because they are nohler and more spiritual, being com- pacted of the subtler part of the egg wherein the fomtative virtue is stronger. When this has happened one of the aforementioned two passages which spring from the heart branches into two, one of them going to the spiritual part which contains the heart and dividing there in it carrying to it the pulse and subtle blood from which the lungs and other spiritual parts are formed, and the other going through the diaphragm (dyafnmna) to enclose within it at the other end the yolk of the egg, around \\ hich it forms the liver and stomach. It is accordingly said to take the place of the umhilicus in other animals and through it food is drawn in to supply the flesh for the chicl-;'s body, for the principle of generation of the radical members of the chick comes from the albumen but the food from which is made the flesh filling up all the hollow: is from the yolk.

After ten days, Albert goes on to say, all the constituent organs are mapped out and the head is greater then than the rest of the body put together. He observes that the yolk liquefies early in development (see Fig. 7) and that slimy concretions are present in the allantoic fluid

‘later on (uric acid). But the passage quoted demonstrates that before further progress could be made some better name must be found than

89 A HISTORY or EMBRYOLDGY

nth . . V g " ~ s“u€ct1:]1::l'lOf membrane to which the first vessel proceeds for a given

Albert, however, was accomplishing a good work one of his bag, amplifications of Aristotle was his description of the relationship be- tween yollr and embryo in fishes. Just as his words about the chick demonstrate that he must have opened hen’-5 eggs at diflerent stages during incubation, so his words about fish eggs show that he must have éhssected and examined them also. In Book vr, tmdate n, chapter 1, he

ays,

Between the mode of development (anatlramzlzmgmeralionit) of birds‘ and fishes‘ eggs there is this ditference; during the development of the fish the second of the two veins which extend from the heart does not exist. For we do not find the vein which extends to the outer covering of the eggs of birds (which some wrongly ull the umbilicus beause it carries the blood to the outside parts) but we do find the vein which corresponds to the yolk vein of birds, {or this vein imhibes the nourishment by which the limbs increase.‘ Therefore the generation of the fish embryo begins from the sharp end of the egg like that of birds, and channels extend from the hart to the head and eyes and first in them appear the upper parts. As the growth of the young fish proceeds the yolk decreases in amount being incorporated into the members and it disappears entirely when development is complete. The heating of the heart, which some all panting, is tnnsmitted through the pulsating veins to the lower part of the belly carrying life to the inferior members. While the young fish are small and not yet fully developed they have veins of great length which take the place of the urnhilieus, but as they grow these shorten till they contract into the body by the heart as has been said about birds. The young fish are enclosed in a oovering just like the em- bryos of birds, which resembles the lure mater and beneath it another con- taining the foetus and nothing else, while between the two there is the

moisture rejected during the creation of the embryo.

Albert also described ovovivipztrous fishes but it is more difficult in that case to tell whether he had himself seetrand dissected them. He notes also the prodigality of nature in producing so many mar-me eggs only

destined to be eaten. _ _ In Books Ix and xv he treats of the Galenie views on generation and

insists again that there is a seed provided by the female. In Book he gives his opinions about the animation of the embryo, quoting the vieus of the ancients as given in Plutarch, e.g. Alexander the Pcnpatetxc, Empedocles, Anaxagoras. Th°°d°“-‘S and Th=°P_h“‘3'7“5- ‘he P°"P“' tetics, Socrates, Plato, the Stoics, Avicenna and AnstotIe,.“who saw the truth,” but, and it is interesting to notice it, never the Chnsuan Fathers.

1 Le. there is I yolk-no but no nllantais. 9° EMBRYOLOGY FROM GALZN TO THE RENAISSANCE

whose writings must have been well known to him. In dismissing the Aristotelian view; he compares the menstrual blood to the marble and the semen to the man with a. chisel in his hand.

On the question of epigenesis and prefori-nation, he follows Aristotle almost word for word, using the same analogies, such as the “dead eye" and the sleeping mathematician. Here his scholasticism comes out clearly, for in rejecting altogether the theory that one part being formed then forms the next part, he says, not that A would have to be in some way like B, but is not, as Aristotle had, but simply Genmzn: ct genera- lum, ext rimul met at nan esrzt, quad omnina ert impa.t.t1'bz'le~a high- handed and very unscientific manner of settling the question. In con- formity with his theology and in contradistinction from Aristotle he makes the vegetative and sensitive souls arrive automatically into the embryo but the rational soul only by a direct act of God.

His mammalian embryology presents some points of interest. He follows Hippocrates (”Ypocras") in an account of the co—operation of heat and cold in member-formation, and he holds very enlightened views about foetal nutrition.

It appears therefore that the embryo hangs from the cord and that the cord is joined with the Vein and that the vein extends through the uterus and has blood running through it to the foetus like water through a canal. Round the embryo there are membranes and webs as we have seen. But those who think that the embryo is fed by little bits of flesh through the cord are wrong and

‘lie, because if this were the case with man it would happen also with other

animals and that it dos not do so anybody can find out by investigation (per rzlratlramyam).

Finally, it is typical that in Book xvxr Albert repeats what he has already said i.n Book VI about the generation of the hen out of the egg all over again with slight changes, but he adds the significant biochemical remark that "eggs grow into embryos because their wetness is like the wetness of yeast.” The importance of Albert in the history of embry- ology is clear. \Vith him the new spirit of investigation leapt up into being, and, though there were many years yet to pass before Harvey, the modern as opposed to the ancient period of embryology had

begun.

7. Aristotle’: Masterpiece

Albert's writings were often copied and printed intbe next few centur- ies, and even as late as :60: De Seam‘: Ilfuliemm. an epitome of his books on generation, was published. In some sense, it still is, as it forms

91 A IIIBTDIIY or EIHBRYQLOGY

• .::::';'::;:;‘::°:;::°.:°;: ’,’"‘;°"€" M-~m or «we»:

Secrthlr in the Cai Coll ‘g m M" -W" 71“ °‘’*’’’. °‘ "‘° 1?’ . H . "5 98° Library 1135, Written across the title-page in ‘add ‘“k_'_ S‘’’_‘’‘’‘".’‘' ’‘‘"‘“’03. duplex iniquitizr, Nathan Emgnm, NW_ 20. 1613. But in spite ufMr Emgross, Albertus, rightly mlled M; us has had the happy fate of being beatified both by the Church angrilb I science. Y

The exact relations between Albertus’ De Secrets} 1‘i!uI¢':r-um and the i""“m‘”‘b'° ‘3°mP°“d-i3 Of P01711131’ booldcls an generation which ap- Pmed in the following centuries, often under the title Aristotle’: Illarterpiere, are complicated and would fittingly provide the subject for a serious historical research This would be of great interest since it is pmb3b1Y °°“°“ ‘° 53)’ 1551! these booklets, reprinted and mddified 2 hundredfold, formed, and still form to—day, the main source of in- struction on sexual and embtyological rnzttlcrs for the world.ng—clz.ss populations of Western Europe. I give in the bibliography a small selection of title of these puhlimtions, which shade of? into such modifications as those of Alletz, who improved upon Albertus Magnus by cutting out all the teaching on generation and substituting a collection of recipes. The bibliography of the D2 Stfltlix has been approached in a preliminary way by Ferckel, whose full paper an the rbjems unfortunately only listed, not printed, in the Sud.hofi'-

C-SL5 J

One of the sources of An'r!alIe’r l'vIa:mpx‘:rz is undoubtedly For- tuniua Licetus, D: lllonmamm Nnlura. The illustrations of 16x6 are still being reproduced to-day. The whole subject has lately been re- viewed by d‘Arcy Power.

This is perhaps the place to mention a curious mediaeval supersti- tion, namely that the development of the human foetus might be un- duly prolonged. The prales Iunarica was a rare kind of embryo which waxed Ind waned with the phases of the moon, thus mnlcing no pro- gress. In the collected miracles of King Henry VI of England (Gros- jean) there is mentioned a pregnancy of tuventy-eight months‘ duration. which was terminated at the intercession of the saint so that the woman produced a child “without deformity or rnonstmsity, such as oft-times belallcth in such cases as this." We may be forgiven for thinking twice about the probable origin of such a tale, since, as may be seen from the comprehensive review of Hamlett, the normal hibernation of embryos

in many mammals is well known; to say nothing of the diapause of the silkworm. ' ’ Arehiul. d. Gazlr. :1. Med. 1923. 92 EMHRYOLOGY FROM GALEN TO THE REN'AlSSAl€C!-I

8. Scholastic Ideas on Generation

Thomas of Aquino (1227-1274) incorporated the Aristotelian theories of embryology into his Smmmz Theologica especially under the head De prapagaliane lmnu'rn': quantum ad corpus.‘ There are some striking passages, such as

The generative power of the female is imperfect compared to that of the male; forjust as in the crafts, the inferior workman prepares the material and the more skilled operator shapes it, so likewise the female generative virtue provides the substance but the active male virtue makes it i.nto the finished product.

St Thomas‘ theory of embryonic animation was complicated.‘ He had a notion that the foetus was first endowed with a vegetative soul, which in due course perished, at which moment the embryo came into the possession of a sensitive soul, which died in its turn, only to be replaced by a rational soul provided directly by God. This led him into great difficulties, for if this scheme were true, it was difl-icult to say that man generated man at all; on the contrary he could hardly be said to generate more than a sensitive soul which died before birth, and on this view what was to happen to original sin? As Harris has put it,‘ Plato had said that the intellect was the man, using the body as a boatman uses a boat. Averroest had said precisely the opposite, namely that the essence of humanity was in the body, and that the intellect was some- thing extrinsic, not limited to the individual, but common to the race. Aristotle had taken the middle position, and given it soul to plants and animals, but, in doing so, he had made it into a vital rather than a psychological principle. The task of combining this v;-1:11’, with the onima of the Fathers was what scholastic philosophy had before it. No wonder that St Thomas’ account of embryonic animation was open to criticism. An echo of it appears in a poem of Jalal al-Din al-Rflmi (x 207- 1273), the greatest of the Persian Sufi poets, and an exact contemporary of St Thomas Aquinas:

I died from mineral and plant became;

Died from the plant, and took a sentient frame; Died from the beast, and donned a human dress; When by my dying did I e’er grow less?

' See pt. 1, qu. lnvi, art. 3 : qu. cxix. art. 2; aviii, mm. x and 2; pt. m, qu. xnn, "1; 4; qu. xxxin, m 1’. Cf. Lecky, Hixlmy of Ratfonalirm, vol, 2, 360. n. 2. I See the special rtudies by Mitterer and Barbado. I Seam. vol. 2, pp. :54 H. Muhsrnmad ibn Ahmad nbn Rushd of Cordwn. AD. H16-H98, one of the zrutesz of Muslim plulosopbu-s.

93 A HISTORY OF EMBRYOLOGY

Duns Seotus (i266—x3o8) 0 ‘med to 5, man)”. '1 8'0"“: already mentioned. anldlhe himself abandoned the and sensitive souls altogether in his De Renmi This saluting was no hetter than that of St Thomas, for agreeing with the {mg 3, Duns d.Id“liI3K theuatiarial soul was not an ordinary fom: "eduoed" f"°“‘ P°‘¢l|9Ia1ity'_ of the material, but xather an udlior creation of G0!‘ llljcdbd by divine power into the embryo at the appropriate m°m¢mi 31 W19 difficult to see how the spiritual effects of Adam's {all could be transmitted to the men of each genuatiun. It was as if only acquired characteristics were inherited. But the further course of 9“‘b"!'°l0giul theology need not he pursued here; it runs in every °¢m“'}' Parallel with true scientific embryology, and it is not my pur- pose to do more than take a glance at its progress from time to time.

In the Spoculiun Nalurale, which was written about x250, by Vincent of Beauvais, the embryology of Consmntine the African appears ayinfl and the embryology of Aristotle, Galen and the scholastic: is to be found in Dante Alighieri (1265-1321), who dealt with the subject in his CoIm'vio,I and mpeiially in the Divine Comm:di'a.' In Canto xxv of the Purgafnrin, Statius (the personifiiztion of human philosophy enlightened by divine revelation) is made to speak to the poet thus:

Ifthy mind, my son, give: due heed to my word: and take: them home, they will elucidate the qutstian thou dost uh. Period blood which is in no casedrawnfromthethiistyreins, hutwhichremainshehindlikefoodthatis removed from table, receives in the heart informing power for all the mem- bers of the human body, like the other blood which umrsathrough theveins inordertoheeonvenedintothosementhers.AB.erh¢ingdigeuteda:eound time it descend: to the part whereof it is more seemly to keep silenoe than to speak, and thence it alterwlrds drop: into the natural ltcephde (the meme) upon mother‘: ‘blood; there the one ‘hlood and the other nnngle. One is appointed to be passive, the other to be active ace-a_rdxi:g _!o the perfed pl=4= whence it proceeds (the heart). And heing united with rt opeflflu am by coagulating it. and than by vivifyinz that In “W1 " ‘"1’ 8”?" “'3' aistency. so that thexe may be material far it to upon (:90: amw. _l-‘I45 eheper.tuainai:ri'a]e' conrlaxe). The active powerh:Vl1_1E b°°““‘°'i‘"'8¢'3f"_'] soul like that of: plant—onlydifl’ering{rom itin this. ‘hit the {°"“" '5” progress while the latter has reached its goal—thetcafi¢l’ “jlfh 50 {N155 d‘‘‘ it menu and feels like: sea-t'ungusautlas_t.|Ie neflfufic "_"h5_ "‘ hm‘! “’ provide with organs the facultks which spring from IL A1 Pm“? my”? the power which proceeds from the heart of the begmer 39 3P”‘°d ’“

' See cap. and xxn. ' fig - . ’Tn:garm1‘:'unt:':s. A eorrimentaty on Dante’: view of ¢m=m-=n 5” 5”“

givenby del GIudin_ 94 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

developed, that power in which Nature is intent on forming all the members, but how from being an animal it becomes a child, thou seest not yet, moreover this is so dilficult a point that formerly it led astray one more wise than thou [Averroes], so that in his teaching be separated the active “intellect” from the soul because he could not see any organ definitely appropriated by it. Open thy heart to the truth and know that as soon as the brain of the foetus is perfectly organised, the Prime Mover, rejoicing in'this display of skill on the part of Nature, turns towards it and infuses into it a new spirit replete with power which suhsuines into its own essence the active elements which it finds already there, and so fomis one single soul which lives and feels and is conscious of in own existence. And that thou xnayst find my saying less strange, bethink thee how the heat of the sun passing into the juice which the grape distils, makes wine.

Having said this, Statius, with Virgil and Dante, passes on to the seventh ledge in Purgatory. It is interesting to see how Dante emphasises the dynamic teleological side of Aristotle and practically speaks of the soul erifleshing itself and arranging organs for its faculties. The reference to Averroes is explained by the fact that Averroes was a traducianist, and held that all the soul was generated by man at the same time as the body, whereas both St Thomas and Dante, as Creationists, held that each fresh soul was a special creation of God inserted by him into the hi-ain of the embryo.‘

The activity of Dante’s contemporary, Mondino de Luzzi (r27o— x326), brings us to the more practical aspects of embryology at this period. Mondino is the most outstanding figure among the Bolognese anatoi-nists in what is really the first period of the revival of biology. After him, as we shall see, biology languished for a couple of centuries

. ‘ A concise account of these controversies is given by Shedd. According to him the views of the primitive Church ran in three directions, though not with equal iitrerigth, nor to an equal urent, Pre-existence, Creationism and Tradueianisrn. Pre—existcnce. associated mainly with the namis of Origen, Cyril of Alexandria and Nemesiua of Emua. taught that all finite spirits (human souls) were created at the beginning, before ‘the creation of matter. They simply took up their residence in the bloodaeed cosgula

‘In rotation" as these were made ready. Thia view did not outlast the fourth ctn!ury— lemme says it is . mm ersuario to believe our "souls were «area of old by God and kept in a treasury.‘ Creationism, don-.'iniu-it among the Eastern ‘Earthen, taught that at some in: during development, a new soul is created dz mliilu by God, and infused into $2 emhryn. The body, on the other hand, derives from Adam by propa- gation. For the souls, an infinite number of creative nets are necessary; for the bodies, only one. Tnduciariiscn, dominant among the Westem Fathers, taught that both souls and bodies derived from Adam, so that in generation, both parts of man ar_I: dci-iyed from his parents. This was 'l'ertul.lian'i view, and it was more or less implicitly ‘d°l>ted by Augustine. , _

In the ltliddle Ages, Creationism prevailed over '1':-aduciaruarri because the latter doctrine seemed to coufliet -with orthodoxy on immortality. At the Refoi-inati_on, with the revival of Augusui-iianisrn, Tnducinnism also returned to favour. lt ll obvious that these changes aflee-ted the outlook of the theological ernhryologuis. '_'A very worthy Subject of philosophical Enquiry,” remarked Sir John Hill, “because impossible to be determined."

95 A HISTORY or EMBRYOLOGY

until the advent of such men as Ulysses Aldrovandus ' th ' . th

’1:““"Yo ‘W1 Singer has shown that this was probablyliiue loslixiiecciict

t anatomy professors did not dissect in person. A forlibri em}; .0. tomy was infrequent. I’ bBut 1:‘1ondmo‘a Anotlxonriaf. published in 1316, contained staternents a ‘out 1 e organs of generation which were rather important.‘ He re- tains the notion of the seven-celled uterus, which had been introduced by'l\flichael Scot, but he adopts a reasonable compromise between the opinions of Galen and Aristotle on the physiology of embryo formation, The distance between him and Leonardo da Vinei (r452—i5x9) would, however, be estimated rather at five or six centuries than at the century and a quarter that it actually was.

9. The Insights of Leonardo da Vinci

Among the artists of the Renaissance Leonardo was not alone in his nnatomical interats, for Michaelangelo, Raphael, Diirer, Mantegna and Verroochio all made dissections in order to increase their knowledge of the human body. But he perieti-.ited more curiously into biology than they did, and he will always remain one of the greatest of biologists, for he first introduced the quantitative outlook. In this he was some four hundred years ahead of his time.

Leonardo's embryology is contained in the third volume of his notebooks, Quoderni d’Anatorm'u, published in fatsimile by the admir- able labours of three Nonvegian scholars, Vangensten, Fohnahn and Hopstock, in 1911.‘ His notebooks are a remarkable and, indeed, charm- ing miscellany of anatomical drawings, physiological diagrams, archi- tectural and mechanical sketches and notes such as “Shirts, hose and shoes," "Go and see Messer Andreas,” "get coal," “the supreme fool (is the) necromancer and enchanter." _

His dissections of the pregnant uterus and its membranes are beauti- fully depicted, as can be seen from the figures which are here reproduced Plate V). He was acquainted with arnnios and char-ion. and he knew that the umbilical cord was composed only of vessels, “laugh 11¢ _5°¢m5 to have thought the human placenta was eotyledonous. There is one drawing which the editors suppose to rt.-priesmt the §.€V§bQp*.X\g hens egg, but I do not feel that this ascription is likely. Indeed, Leonardo worked with eggs much less than with mrirnmalian embryos,‘ though there are references to the foi-mer. ‘See how birds are nourished llfl their eggs," he says in one place, to remind lumself, perhaps. Of P055“? 5

I \V:indI:r reproduces the obstetrical illustration of this p=n'od- - See also the book or McMi.irrich on a. 96 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

experiments, and, elsewhere, "Chickens are hatched by means of the ovens of the fireplace." Again, "Ask the wife of Biagino Crivelli (was she the Lucrezia Cr-ivclli, whose portrait Leonardo painted?) how the eapon rears_:1nd hatches the eggs of the hen when he is inebriated,” a subject recently reopened by Lienhart. “You must first dissect the hatched egg before you show the difference between the human liver in foetus and adult.” Leonardo perpetuates a persistent error in the note, "Eggs which have a round form produce males, those which have a long form produce females.” Concerning the mammalian foetus, he says,

The veins of the child do not ramify in the substance of the uterus of its mother but in the placenta which takes the place of a shirt in the interior of the uterus which it coats and to which it is connected but not united by means of the cotyledons. ‘

Thus in one sentence Leonardo falls into a mistake in saying that the human placenta is cotyledonous, but at the same time asserts a fact which it took all the ingenuity of the seventeenth century to prove to be true, namely, that the foetal circulation is not continuous with that of the mother, for the placenta is only connected to the uterine wall and not united with it. Leonardo goes on to say,

The child lies in the uterus surrounded with water, because heavy things weigh less in water than in the air and the less so the more viscous and greasy the water is. And then such water distributes its own weight with the weight of the creature over the whole body and sides of the uterus.

The tendency towards quantitative and mathematical explanations is apparent at once.

Further notes are, “Note how the foetus breathes and how it is nourished through the umbilical cord and why one soul governs two bodies, as you see the mother ,desiring food and the child remaining marked (by a given amount of growth) because of it. Avicenna pretends that the soul generates the soul and the body the body. Per emmz." The child, says Leonardo, secretes urine while still in utrro, and has excrement in its intestines; at four months it has chyle in its stomach, made perhaps from menstrual blood. But it has no voice in ulna, “when women say that the foetus is heard to weep sometimes within the uterus, this is rather the sound of some flatus. . . .” Nor does it breathe there (on this point Leonardo contradicts himself). “The child does not respire within the body of its mother because it lies in water and he who breathes in water is immediately drowned.” “Breathing is not necessary to the embryo because it is vivified and nourished by the life and food

n.r.—7 97 A HISTORY OF EMERYOLOGY

of the mother." Nor does the embryonic heart bug. To us ‘ht smemcm that there is no respimtipn the uterus is obviously false, but we mean by the word tissue respiration, whereas in Leonardo’s time pulmonary ‘°5P”‘“'°" “'35 lmendflli he was therefore perfectly right in denying that the embryo breathed, as certain anatomist: before him had asserted. His only reference to the soul runs thus:

_ Nature places tn the bodies of animal: the soul. the composer of the body, r.e. the soul of the mother. which first composes, in the womb, the shape of man and in due ruwrkens the soul which shall he the inhabitant thereof, which first remains asleep and under the tutelage of the soul of the mother which through the umbilical vein nourishes and vivifies it.

This is not very revolutionary. But Leonardo was the first ernbryologist to make any quantitative observations on embryonic growth; he defined, for instance, the length of a full-grown embryo as one braccio and the adult as three times that.

The child grows daily far more when in the body of in mother than when it is outside of the body, and this teaches us why in the first year when it finds itself outside the body of the mother, or, rather, in the first 9 months, it does not double the size of the 9 months when it found itself within the mother’: body. Nor in 18 months has it doubled the size it was 9 months after it was born, and thus in every 9 months diminishing the quantity of such increase

till it has come to its greatest height.

Here Leonardo touches on one of the most modern quantitative aspects of embryology, and one almost arpects to see him exemplify his words with a graph until one remembers with a shock that he lived two cen- turies hefore Descartes and live hefore Minot (see Fig. 5). His numer- ical data may also have included figures about the relative size: of the parts. and the germ of the line of rrsezu-ch so successfully pursued by Scarnmon and Calkins in our own times may be found in the note, “The liver is relatively much larger in the foetus than in the grown man." Other quantitative notes conoem the length of the embryonic intestines, as in the laconic “zo hraccia of bowels" and the statement that "the length of the umbilical cord always equals the length of the foetal body in man though not in animals.’'‘ ‘

He said little about heredity, hut in one place he mentions a arse of sexual intercourse between an Italian woman and an Ethiopian,‘ the outcome of which assured him that blackness was not due to the direct action of the sun and that the “seed of the female was as potent as that of the male in generation." Finally, the best instance of the wider-ress of

x Lmmma would have enjoyed Fog‘: statistical study of sooo umbilical card:

(1939). 1 98 EMDRYOLOGY PROM GALEN TO THE RENAISSANCE

snunzmnsus so is so 10: no us use 165 no in ..

Fig. 5. Decline af the mung: growl}:-rat: with inumsing Hg: in hufiin male: (_/mm Illimzr).

his thought appears in the note, "All seeds have an umbilical cord which breaks when the seed is mature. And similarly they have matrix and secundines as the herbs and all the seeds which grow in shells show." We have met this idea before in Hippocrates of Cos, and we shall find it again in Nathaniel Highmore.

It is no coincidence that pictures of weights and cogs and pulleys stand side by side in Leonardo's notes with anatomical drawings of the embryo. As Hopstock says, "Leonardo arrives at the conclusion that there is but one natural law which governs the world, Necessity. Neces- sity is Nature's master and guardian, it is Necessity that makes the eternal laws." If Aristotle is the father of embryology regarded as a branch of natural history, Leonardo is the father of embryology re- garded as an exact science.

10. The Macro-iconographers of the Sixteenth Century

After such a man, the writings of his contemporaries, such as the mythical Johannes de Ketham, Alessandro Achillini and Gabriele dc Gerbi appear beyond description inferior.‘ De Ketham’s embryology has been described by Fercltel. De Gerbi included in his Liber Ana- tamiae tarpon": humani et ringulomm membronun iIIx'u: a section entitled D: Generations Embryonix, but there is nothing to be said about it except that it is a verbose compilation of the views of Aristotle and Galen taken from Avicenna. The work of Nolanus in 1532 presents

‘ Ct’. Weindlerh Gerrhirlxtc d. gjwdhologixeh-anaramzirhe Abbx'Idun.!- The contem- P0l'I1'yu§!Dd|l':]dOl'I$ of Levinus Lemnius (described by Cole) Ind by Pctru: Clndldlll are wx out \ ne.

99 A msronv or EMBRYOLOGY

fcnain points of interest, but it is of little importance. Petrus Crescentius

1 hm “wk °“ husbandry °f 1548 mmfivfls artificial incubation in ovens

ut rather as a lost art. About this time also Hieronymus Dandin - Ccsem-8: 3 .l€5“if. Wrote a treatise on Galen's division of o s white and red. those proceeding from the semen and those prriatieding filolxsnutlltaibloodz it is cited by Aldrovandus, but I have not been able to

The most remarkable feature of the first half of the century was the encyclopaedic group of zoologists which now arose. This Belon and Rondelet, whose well-illustrated catalogues of animals were appearing from 1550 onwards. did a good service to comparative embryology in figuring the ovoviviparous selachians and viviparous Cetncea. Gesncr belongs to this group.‘ All of them reproduce thin versions of Aristotle when they speak of generation as such, and this is what dhfcrentiatesi them from Ulysses Aldrovandus, of whom I shall presently speak. Fig. 6 A and B shows Rondelet's picture of a viviparous dolphin and an ovoviviparous selachian!

But the end of the twilight period was now at hand, for, within twenty-five years after the death of de Gerbi in 1505, four great cm- bryologists were born as well as the greatest anatomist of any age, Andreas Vcsalius (1524), of whom I shall say no more, for he had no opportunities {or dissecting human embryos, and took hardly any interest in foetal development. But in x527. Ulysses Aldrovandus was born, and in the following year Gabriel Fallopius, in 153a Julius Cafiar Arantius and in 1534 Voleher Coiter. Only three more years bring us to the birth of Andreas Laurentius and of Hieronymus Fabricius ab Aquapendente, the teacher of William Harvey.‘

The senior member of this group, Ulysses Aldrovandus, was the first biologist since Aristotle to open the eggs of hens regularly during their incubation period, and to describe in detail the appearances which he found there. In his 0rm'lhaIagx‘u, published at Bologna in X599, he set out to describe all the known kinds of birds, dismissing ‘mtum not only their zoologiml and physiological char-actcristits, but also their signifi- cance as presages and for augury, their rnystiuil meaning, their use as allegories and for eating, and finally all the legends respecting them.‘ Gmerarftar, Tzmperantia, Liberalilar, a-guild: one finds. Beginning with

‘ Historic, Pt. HI, 1:. 432. .

I Oppcnhcinjgf has glvrn us - lpeclal stud of Guillaume Rond:leL_ _

’ Since this book was firsr written, I have d the good fortune to vim many at the scenes peopled by thtse great Italians, to find the little town of Aquapendente on the road to Rome, and to come upon the house of Aldronndus unupectedly during a mall through a quiet street in Bologna.

‘Vol. 2, pp. 133 it.

too EMBRYOLOGY I-‘ROM GALEN TO THE RENAISSANCE

B. An (wmiviparoux) xhark. Fig. 6. Illuxlmtiaru/yam Rnndrlefn "De piscibus rnarinis" af155(.

the eagle, he proceeds to the vulture, the owl, the bat (the only vivi- parous bird!), the ostrich, the harpy (l), the parrot, the crow and so to the fowl. Side by side with a reference to the famous poem of Pruden- tius (M ulti um! Pnxbyteri, translated by I. M. Neale) about the steeple- eock, we find an excellent account oi the generation of the chick in the egg. The book is sumptuously illustrated, but unfortunately there is only one picture of embryological interest, namely, :1 chick in the act of hatching.

In Aldrovandus‘ embryology there is much discussion of Aristotle and Galen, but traces of an independent spirit abound. Pliny's view that the heart was formed in the white is “exploded," and Aldrovanclus says that it is formed on the yolk-membrane. He refutes the opinion of Galen also that the liver is firs: formed, in connection with which he says,

101 A HISTORY or EhIBRY(']|_oGy

I00

50

to

5 lo .5 ,0 E7g.7.Wm 1 If (trend in‘ Jim ("W01 oligduugbgu‘ nrzlnelavlopmaunj

In order that I might bring to an end this conlrovarsy between the philo- sophers and the physicians I followed with the ham”: cuxiosigy ma dflj. gence the incubation of 22 hen’: eggs, opening on: cad} d;y;z1;us I found Aristotle‘: doctrine to be the truest, And beans: apm {mm an [35 um these matters are most worthy of being looked iim; thgy pynvidg ;15o 11“; greatest pleasure and entertainment, I have though: it mu :9 dcsq-ibg mm

as clurly and briefly as possible.

Aldrovandus also contradicts Albertus, and pmpounds 3 new them-y, namely, that the apriritualia (the organs in the thorax) are formed from the seed of the cock (2: roan’: srmine start). This sced he afiirmg to be present in the egg, and he identifies it with the chalazae, thus anticipat- ing Fabricius ab Aquapendentc, but not going quite so far. and ex- plicitly opposing Gaza, who had said not long before that the chalauc were simply congealed water. Aldrovandus’ admiration for Aristotle is extreme, and, though he diflcrs from him about the chalaue, he defends the Aristotelian opinion that the chick was made from the white but nourished from the yolk. His argument for this is new, however; it is that, during incubation, the latter liquefies but the former hardens‘; now in all digestion liquefaction takes place, and in all growth hardening.

‘ During incubation the egg-white lose wnter md the yolk, up to I certain point.

pin: it, use Fig. 7. 1:32 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

therefore, etc. This argument is a great deal more cogent than most of those which were current between 1550 and 1650. He goes out of his way to castigate Albertus for saying that the yolk moves up into the sharp point of the egg, for experience assures him that it does not, “as I have observed by cutting open an egg after one day‘s incubation.” A striking instance of his powers of observation was his description of the “egg-tooth” of embryonic birds, a discovery made anew in the nine- teenth century by Yarrell and Rosenstadt. The chick was perfect in form, according to him, on the tenth day.

The peculiarity of Aldmvandus lies in the fact that he incorporated so many elements into one book, and was able to produce a collection of chapters in which good scientific observation sat at the closest quarters with literary allusion and semi-theological homily. So well-proportioned a mixture as the Ornithalagia is not often found. As a final instance three consecutive paragraphs may be mentioned, in the first of which he discusses Plutarcl-Rs arid problem about the priority of egg or hen, next he makes some very reasonable remarks about teratology, suggesting that monsters come from yolks which are physico-chemically abnormal in some way, while in the third he expresses strong scepticism concem- ing the tale that the basilisk is sometimes hatched out from a hen‘: egg- Ego rte jumnlibu: quidnn aediderim, he says. This last notion is found in the fourteenth-century poem of Prudentius alluded to above, and appears again in the Mtircellantmts Exem'!a!t'on: of Caspar Bartholinus the younger,‘ whose second chapter is devoted to showing “That the basilisk hatcheth not from the egg of the hen,” a conclusion which has been amply confirmed in the light of subsequent experience.‘

Aldrova.ndu.s' disciple Volcher Coiter the Frisian,‘ as he described himself, did not sufier from the prevailing vice of the age, verbosity. His Exfenmrmrr et Inlermmzm prfndpalium Hmrmni Co@on': partium tabulae el extrcitationex, which appeared at Nuremberg in 1573—a beautifully printed book—-contained a brief section entitled De ovamm gallinaceorum generutionir prime exovdia progrermque at pulli gallinacei crenliomir ordinz. His Latin style betrays his German origin, for the constructions are Teutonic, though the meaning is always perfectly

cléar. Coiter says,

‘ See Petersen.

- Barrholinus gives a bibliography of this eurioun legend, on which lee also Robin, pp. 84 ff. In an interesting paper L. L Cole he: considered the historical aspects of sex-mmu in (owls; the rmdmey of hens, especially old arm, to develop male characteristics, even to the extent of crowing. Hence the origin of “rock's eggs." nought norcerers as ingredients of mxgiual preparations. Case: of the lctull trial and can emrmion of cocks for laying eggs are on record, 24:. II Basel in 1474- The question hu widbreaching implimtiom. u is shown in the author’: Seizure and Cx'v1'l-

oauan in china, vol. 2, pp, 57;, gr, ' See Plate Vl, facing page r04.

r03 A HISTORY OF BHBRYOLOGY

In the year 1564 in the month of May at Bologna, being instigated by that excellent professor of philosophy outstanding in varied sciences and am, Doctor Ulysses Aldrovnndus and by other doctors and students, I ordered 2 broody {owls to be brought and under «ch of them I caused 23 eggs to be placed and in the aompuiy of these persons 1 opened one every day so that we could see firstly the origin of the veins and secondly what organ is fint formed in the animal.

What follows is practically a repetition of the facts available in Aristotle, hut described with much greater clcarness than either Aristotle or Aldrovandus had been able to bring to the matter. On the third day. he saw the globulin xmgufnnu which in t.-itella nmriifa-It pulinbat, and so solved his first problem. He decides that the firs: organ to be formed is the heart, and quotes Laet.antius' experiments. He explains the large size of the eye as due to the fact that the most complicated part oi the body needs the longest time for its manufacture. .He_correct1y describes the various membranes, and the footer mbt:i'n'dre: in the intestines st hatching. Once he contradict: Aristotle, maintaining "'3' °“ “*9 “Fm day the body as 9. whole is larger than the head. and once he contradicts Albertus, denying that any yolk can be found in the stomach at hateliing. He concludes his tractate by a succinct and clear sccmmt of the opinions of Aristotle and Hippocnts nbout_ ernbryatllc .¢‘l€V¢l‘_’P£’‘°’“- 1;“ importance is that he drew the attention of scientific gm? H5 {O ‘ ; problems arising out of the hen s egg. and 3595195 “" ‘ ° °""‘fi‘!';“_‘!’5 that iconographic phase in embryology Wl1I_€l1 ‘W-5 l3“£_x‘° _ _ ' climax in the plates of I-‘abi-icius. and its close in Harvey"! _ #031110’:-

Gabriel Fallopius, who belongs to this tune. must be_menti_one ‘est e discoverer of the organs which hear his name. but his “*'“°‘’_ ‘’ ‘a bi-yclogy were only indirect. A. Beiiedictus, ttho was now gl:W:‘E ‘:1’:- and Caesar Crernonius, who waastill youlggv WY :°d"m(°:';|m:u5“dso Pfinfipil “P*‘°'d°” °’ P‘"° ’‘’.‘‘‘°'.°1'”3"m' 1}; “Ram of x 65 wrote on the embryo. B. Teiesius, in his De alum {animus ‘gue- studied the hen’: egg and suggested that the pgflfldfhe Wu thud“ formed by []1:,:ressuxt:GOi'1|lh¢ u:1€l§l:;::ngtLS a in . middle term tween I en in - .

Julius Caesar Amati-is has already W *.°‘""‘ §;’a‘?.’.‘.’§3$.":f".‘: FM" W“ ‘H imP°“““ "S’°“' "“" ‘l-'°"gh "iamic to height ‘it deal: the fin‘ when ‘he "mun-lconogmpluc ‘chm d as a constituent of with a rather different field and cannot be consi ere mm W“ kmcd by that grouP- 1* "°8“” bY’°"“”“ M “mi?” mm that he had an ‘“ “°‘-‘5‘l°“‘ “ 3°19?“ " wuple of ye?!" DlTo'ut certain Points in oppommity of testing whethet “‘° °P.”“."”’ 5 dsdurlng the Previous generation, which he had formed an 0PM" 8”“

I04. PLATE VI

Vnldm Cmlu ll): I-‘n'mm, an. 41 (pamltdm 157 5 by an unlmann ymxln, none in [In Smdmtlu Bxlrlmllulc, I\’lIItmberg).

rm EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

fifteen years, were true or not. In the first place, he found on dissection that the placenta was not cotyledonous, and he spoke thus of its fom1a- tion: '

Blood flows out from the spongy substance of the uterus and this blood growing in bulk forms a soft and fungous-like mass of flesh, rather like the substance of the spleen, which adheres to the surface of the uterus and trans- mits to the foetus in proportion as it grows the nourishment for it which reaches the uterus in the form of blood and spirits.

Then, going on to discuss the functions of the jeeur uteri, as he calls the placenta,‘ he devotes a chapter to De vorarum umbilicalium arigine, and contradicting Hippocrates, Galen, Erasistratus, and Aetius, says that the maternal and foetal blood-vessels do not pass into each other by a free passage.

Thk is repugnant to sense, and as may be seen by ocular inspection, these vessels do not reach the inner membrane of the uterus, for the substance of the placenta is placed between their ramifications and the proper substance of the womb.

He was thus the first to maintain that the maternal and foetal circulations are separate, but he naturally did not, and could not, speak of circula- tions, since he lived before Harvey. Nor could he have proved his point satisfactorily with the means then at his command, and, as we shall see, it was to take another century before the proof was given. Apart from this valuable contribution to embryology, Arantius gave some admirable anatomical descriptions of the foetal membranes.

Hieronymus Fabricius ab Aquapendente, the pupil of Fallopius, has always been given an important place in the history of embryology by those who have written on him.‘ As one comes upon him in the process of tracing out that history itself, however, he does not take such a high place. With the statement, for instance, that “Fabricius carried embry- ology far beyond where Coiter had left it and elevated it at one bound into an independent science" I find that I cannot agree. Embryologists who caiied themseives that and nothing efse o’r'n' not appear tifl the end of the eighteenth century, and it seems to me doubtful whether the anatomical advances in embryology made by Fabricius are not counter- balanced by the erroneous theories which he invented at the same time.

‘ Ijlot until the discovery by Claude Bernard in 1858 that the glyoogmic function of the Jrver I9 undensken for the foetus by the placenta, could thejuxtness otthis intuition be assessed at its true value.

' \_\'c are now in possession of the cuznptuous fxtairnile eclidon of Fnbria'ua' embry- ologrczl worlu. edited with I brilliant and exhaustive commentary by my friend Dr Howard B. Adelnunn of Cornell Univmiry (l942)4

ru5 A HISTORY or EMBRYOLOGY

His D: Formation: Q11 2! Pull: and his D: Frmmria Poem of i6o4 show much more scholasucism and sheer argumgmafiveness mm is to be found in Coiter, and are remarkable for their bulk. Fsliricius “ems '° have had 5‘ Emits for exsuccous and formal discussions. He spends much um‘! {°" '”mPl°- in “king “P the problem of whether the yolk of the hen’5 egg is more earthy than the white, and looking at ‘E ‘mm 3" P°55‘bl¢ a_ngles. He disagrees at last with Aristotle and de- cides that the white is the more earthy. Bone, he says, are white, but also very earthy. The albumen is colder, stielder and heavier than the yolk: reqmlur, rmertrfur me. In addition, he introduced a number of grave errors and misleading theories into embryology, so that subse- quently Harvey had to spend a large part of his time refuting them. Fabricitis was, indeed, a good comparative anatomist, and it is upon

. that ground that he deserves praise: his‘ plates, some of which are

reproduced herewith (Fig. 8), were far better than anything before and fora long time afterwards. He dissected embryos of man, rabbit, guinea-pig, mouse, dog, cat, sheep, pig, horse, ox, goat, deer, dogfish and viper, a comparative study which had certainly never been made previously.

In his first tr-actate he begins by dealing with a question not unlike that of how the sardines got into the tin, i.e. how the contents get into the hard-shelled egg. He rejects Aristotle's idea that the egg is formed in the oviduct by a kind of urnbilicus, and ascribes its growth there to transudation through the blood-vessels. He rnarlts a definite advance upon Aristotle when he says that sillrworiris and other insects are born into their larval state from an egg, though he still terms the chrysalis an egg, and therefore holds that they are generated twice. Then fullovss his discussion of what part of the eg the chick comes from. The chalazae, he says, are not semen, for the semen is not present at all in the fertilised egg. His argument sounds peculiar when he says that both the white and yolk of the egg are the food of the embryo, for neither of than is absent at the end of inuibation, therefore neither of them is its material. Hippocrates had said, ex lutea gzjgni, ex like nurriri: Aristotle had said, at albo fieri, ex Iutea nutriri. The latter was the View generally held in the sixteenth century, as may be gathered from Ambrosius galepinus dictionary; Senligefs Commentary on Arirtnrle and the treatise on the soul by Joannes Philopanus.‘ . _ _ _ V

Fabricim now says both nourish, neither makes. This distinction between food and building-materials seemsto us unD€°¢S331'Y. 511$“ had a great influence on later thought. Fahricius devotes much tune to proving, as he thinks, that yolk and white are of the same nanire. and

‘Bk.r.ch. :. 11:6 F1}. 3. Illuxnabiom from I-'a6n'a'm a6 Aqucpmdaxlzfi "37

"De Formation: Ovi ct PuII.x'," 160;. A HISTORY OF EMBRYOLOGY

adduces the fact that “in cooking the white hardens first, whether the egg be boiled or poached. but the yolk hzirdens also if the heat is

mOf;:" comparing the heat of the kitchen to the innate heat of the chic

But you will say [he goes on] ifthe albumen and the yolk are the food of the chick in the egg, what then must we decide the material of the chick to be. since we have already aid that the semen is not present in the eggs. You will find this material from an enumeration of the para of the egg-there mnains only the shell, the two membrane, and the chalazae—nobady will assign the membrane: or the shell as the rnaten‘.-il nf the click, therefore the nhnlazae alone are the fitting substance out of which it an be made.

Having discovered this truth by the infallible processes of logic, Fabri- cius brings all kinds of arguments forward to suppart it; he adduoes the three nodes in the chnlazae as the precursors of brain. heart and liver; tadpoles, he thinks, resemble significantly the chalazac, being "arrnlrss lgglcss spines." The eyes are transparent, so are the chalazae, therefore the latter must give rise to the former. The liver is formed as soon as the heart but is prtctically invisible as it does not palpitate. One of his most gratuitous errors was the suggestion, now newly introduced, that the hem (and other organs) at the foetus has no pgorer fim$tx°n- W mwm: publicum, but beats only in order to preserve llS'O.Wfl life. Then there is a considerable section called D: Ovomni Ulxlttaiihftti Whwh almost does for the hen’: egg what Galen’s D: Um PlfVf1llm.dld for the human body, and in which such questions as tvhy the shell is hard and porous? and Why there are any me_mbi-ants In thc 628? are “km PP and answered with an elaborate display of commtm 565155 The '9' fluence of Galen is perceptible in a passage about a liver-like !\1b$§=|I*°° being formed if blood is freshly shed into hot ymter, in the _usua ’l)¢'l’~ minalagy of formative faculties. and in the division of flashes into w ite and red, though the former is not specifically derived fro]? tin; s_en:'eer: nor the litter from the menstrual blood. The human P ct: bl’ the scribed as eetyledonoue, and needles: confusion I3 cf”! ‘mYd the doctrine that the “liquors, hummlflv °' '_=*‘h°"- “mm”? "t;'°mni°3 foetus. are two in n"m‘=='- SW” 3”‘ “‘?“" ‘he iiim :31 hf Fabri: the latter in the allantois." But the dmwmgs and ‘J Ermthat it Wm t:ius' work are beautiful and accurate, so much 5%. E 63 I sagas of lung remain 3 HIYSWTY h°"": thc mm ‘Yb? fig?" h e-em like blood. the dewbpmem of the as Fabnqus dmiisishzmngeen able to Ves==‘5 "*‘“=“i*‘E ‘“3"‘ "‘° “““'"° hm’ mu th ‘izeiaterial of the propound the thesis that the chalazze were 5

embryo. r08 EMBRYOLOGY FROM GALEN TO THE RENAISSANCE

The other biologist to whom Harvey was most indebted was Andreas Laurentius of Montpellier, whose Historic Anntantita (printed with his other works in r628) contained a whole book (vn) devoted to embry- ology. but which presents us with nothing except a commentary on Hippocrates and Aristotle. The only evidences of life are fumished by two polemics, one of which was against Simon Petreus of Paris, who had propounded some new views about the foetal circulation. Laurentius gave also a table showing the changa which occur in the heart and lungs of the foetus at birth.

It was about this time that the embryologiml observations of that many-sided genius, Hieronymus Cardanus, began to attract attention. His main thesis was that the limbs of the embryo were alone derived from the yolk, while the rest of the body came from the white. This was a well-meant attempt to mediate between the two traditions headed respecfively by Aristotle and Hippocrata, but the arguments in support of it were not remarkable even for ingenuity. Constantinus Varolius treated of the formation of the embryo in a book which appeared in 1591, but very inadequately.‘ He had certainly oped hen's eggs, and describes the fourth—day embryo as found mim'mi fa:-cola‘. But nearly every one of his marginal headings begins with the word Cut, and this tells its own story, for the didactic style rarely hides guruine works of research. Johannes Femelius, a rather earlier worker, in his De Homz'm'r Plncrmtione followed Aristotle and Galen in nearly all particulars, and made no real contribution to embryology.’

xx. The Movement to Rationalise Obstetrics

On its practical obstetriml side the sixteenth century produced some remarltable compilations of ancient gynaecological writ'mgs. The first of these was that of Caspar Wolf, which was published at Ziirich in 1566, and, after having been enlarged by Caspar Bauhin in r586, subsequently formed the backbone of the most important and famous one, namely that of Israel Spach (Strassburg, r 597). Although these composite text-books repruented no real embryological progress, they yet showed that great interest in development was alive, an interest which. though doubtless utilitarian in its origin, could hardly fail to lead to advances of a theoretical nature. (See Fig. 9.)

The obstetrical literature intended for midwives is also of great

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n9 EMBRYOLOGY FROM GAL!-IN TO THE RENAISSANCE

interest. It was about this time that the first popular guides to their subject began to appear, founded not upon mere superstition and the remnants of ancient knowledge derived in roundabout fashion through Syriac and Arabic, but either upon a careful study of Galen and Aris- totle, or upon the results of dissections and living speculation. The principal representative of the former class is that oflacob Rueff, which appeared in 1554 and was called De Cnnceptu ct Generation: Haminis. Although written in Latin, it was soon translated into the vemacular languages. Its importance lies in its illustrations, which I reproduce in Fig. ro. I think they show very clearly what the general ideas were at this period about mamrnnlian embryology, and thus alford us a precious insight into what was in the minds of such writers as Riolanus the elder, Mercurialis, Saxonia, Rondeletius, Venusti, Holler and Vallesius. There are many points which their expositions of foetal growth and de- velopment leave vague, and without Ruefi it would be diflicult or impossible to picture in what manner they imagined it to go on. Rueif’s text follows Galen and Aristotle with fidelity, as does theirs—with t.he exception of a few minor ideas not quite consonant with this.

In (a) of Fig. ro Ruefi portrays the mixture of semen and menstrual blood in the womb, or, as he loosely refers to it, of both seeds, coagu- lating into a pink egg-shaped mass surrounded with a fine pellicle. (b) shows the some mass in the uterus and wrapped round with the

‘three coats, amnion, chorion and a]lantois%a lamentable but interest-

ing misrepresentation of the facts. Then in (c) it is shown that upon the surface of the yolk-like mass of semen and blood appear “three tiny white points not unlike coagulated milk,” these being the first origins of the liver, the heart and the brain. Next (:17) shows the first blood- vessels springing from the heart, four in number, and distributing them- selves over the surface of the mass. It is plain that Rueff must either have opened hen’s eggs himself and seen the early growth of the bIasto- derm or have been told about it by some observer such as Coiter or Aldrovandus. He could not have copied his pseudo-blastoderm picturx from their works, for in r 55.1, none of them had appeared, and, as

far as I la-row, there were no similar illustrations in existence at

that time.

After this point the pictures grow even more fanciful, and, in (e), the first outline of the cranium is seen taking shape in the upper part of the “egg." In (f) the blood-vessels have suddenly assumed the outline of a human being. and in (g) the finished product is seen. Rueff gives what seems to be a mnemonic in hexameters:

‘ On the elusive human allantois tee Meyer (1954).

III A HISTORY OF BMBRYOLOGY

iniectum semen, sex primis certe diebus

est quasi lac: rehquisque novem sit sanguis; at inde mnsolidat duodena dies; bis nona deinceps

cfligiat; tempusque sequens producit ad ortum

tahs enim praedimo tcrnpore figura coosit.‘

Rueff gives some excellent diagrams of the foetus in were with rela- tion to the rest of the body, and the various positions which am: familiar to obstetricians. His teratology is less happy, for he attributes the pro- duction of monsters to the direct action of God, though he does venture upon a few speculations concerning “corrupt seed.” But his principal significance for this history is that in his picture of the yol.lt—like mass of mixed semen and blood, with the pseudo-blastoderm upon it, he throws a brilliant light on the Aristotelian conceptions of his time.

These beliefs lasted far on into the eighteenth century (see p. 183). Thus as late as 1683 we find, in the English translation of Mauriceau's midwifery:

Hippocrates relates tl story of a Woman, which at six days and cast forth. with a noise, at once, out of her Womb, the seeds she had oonoeived, resem- bling a raw Egg, without a shell, having only the small skin over it; or, to the abortive Eggs which have no shell: which membrane was on the outside a little covered with red.

Ruefi’s book was subsequently tmnslatcd into English, and had many gditions as The Expert Iilidmfe.

The principal representative of the second class of popular books of this period is that of Euch. Rhodion, Résslin, or Rosslein, which was translated into English, and published as his own work, by Thomas Raynold, "physitiun," in 1545, under the title of The Byrrlr of 'Man- lzymjg atlmwyre named T he Woman‘: Book! It was the firs: book in the English language to contain copper engravings. They were variants of the traditional Soranus-Muschicn figurm Thr: Rfisslein-R5Y"°’d 5°01‘ pays less attention to Galenie theory than does that of Rueff, and in- cludes much better drawings of actual dissections. Another famous obsmrical book was that of Scipio Nlercunuss for further information on Renaissance midwifery see Spencer and Miller. .

The minor cmbxyologists of the sixteenth century included among them Arnbroise Pare, the founder of modern surgery. Hrs teachmg on generation involved nothing original, and sums to have been Galcmsm

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rwice9days(d==f'1‘.” . - d- ~- hgcn destined to have by the ippaknle hme. "‘i‘,:‘,’,,’§‘:.§'n, cmiitii: d.’Arcy Prrwer, and Ballantvne (um).

I12 Fig. :0. 1zImmm'm{;m jaeolz nuqyu “D: Conctptu at Gcncrnion: Homx'nis” of

1554 (arranged Singer), xhottfng flu Aritlottlxail coagulum nf blood and

interpreted by an intelligent. well-balanced, unsgeeulative mind. The three-bubble theory appears in him very clearly; thus, we read. "The seed boileth and fermentethimhe womb, and swelleth into three bubbles or bladdcrs"—-—the brain, the liver and the heart. Pare"s illustrations are copied wholesale from Vesalius and Ruefl”, without acknowledgment. The last authors to lake the three-bubble theory seriously were Robert Fludd in 16x7 and A. Deusingius, who wrote in 1665, after Han-ey. Others who deserve a mention, but no more, were Severinus Pinaeus, L. Bunaciolus and Felix Platter. None oflhem made any advance, and the illustrations of the former’s De Virginilalflvm nolir Graeiditzzle et Pam: were almost ludicrous.

Hieronymus Capivaccius, F. Lioetus, I. Costaeus and V. Cardeliuus, who wrote in 1608, were the last true supporters of the ancient theories, such as that the male mnhryu was mice as hot and developed twice as quickly as the female.