Book - A History of Embryology 1959-1

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I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!

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
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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 1. Embryology in Antiquity

1. ideas of Primitive Peoples

Since biological science as a whole was little cultivated in ancient Egypt and the ancient civilisations of Babylonin, Assyria‘ and India, the study of embryology Wis equally little pursued. Doubtless the undeveloped embryo, whether in egg or uterus, carried with it, for these persons of remote antiquity, some flavour of the obscene in the literal sense of the word. But embryology stands in .1 peculiar relation to the history of humanity, in that even at the most remote times children were being born, and, though the practitioners of ancient folk-medicine might confine their ideas for the most part to simple obstetrics,‘ they yet could hardly avoid some slight speculation on the growth and formations of the embryo. Figure 1 illustrates this level of culture. It is a painted and carved door from a house in Dutch New Guinea, taken irom de Clercq's book ; the original was of yellowish brown wood. The male embryo is clearly shown. but the mist evidently had a hazy conception of the umbilical cord. The line passing from the uterus to the head may or may not be merely ornamental. The movement of the foetus in uttra played and atill plays a large part in the folklore of primitive peoples, as may be read in the exhaustive treatise o[Plass 6: Bartcls. For information concerning god-embryos in prirnitive religion see Br-irfault.' The works of Hutton and of Ashley Mvntagu may be consulted for a mass of information regarding primitive philosophies of life and its development.

2. Egyptian Antiquity

Egyptian medicine did not venture on ernbryological speculation, or so it would seem from the writings which have come down to us——the Ebers medical papyms does not once mention the embryo (Brugsch).' But there are points of interest as regards Egypt in this connection. Que particular aspect of Egyptian thought is certainly of embryologrcal interest, namely the theory of the placenta, recently investigated by Murray.

  • See Zervoa.
  • See R. 1-‘. Spencer. ' ‘I01-_!. P95:
  • A gtntnl um; of ancient Egyptim gynaecology and obstemcs I-I ewm Reinhard.

In Frazer's FoIk~Lare in the Old Testament there is a chapter entitled “The Bundle of Life" in which he discusses the idea of the external soul, and the various receptacles used to contain it. He draws attention to the compliment which Abigail paid to David at their first meeting: “And though man be risen up to pursue thee. and to seek thy soul, yet the soul of my lord shallbe bound in the bundle of life with the Lord thy God; and the souls of thine enemies, them shall he sling out, as from the hollow of a sling.” This implies, as he says, that the souls of living people could be tied up for safety in a bundle, and that on the contrary, when the souls were those of enemies, the bundle might be undone and the souls scattered to the winds.

Murray explains that this was a distinctively Egyptian doctrine, since Syria was an Egyptian province and had been so for centuries. She discovered among the titles of the Egyptian royal officials the significant “Opener of the King's Placenta.” Other evidence demonstrates that the fate of the placenta, fig‘ "" P""""' “mi “""'d d°°' 1"”

_Dutch New Guinea (dz Clercq).

at any rate in the dynastic families, was regarded as of great importance, since it was thought to bethe especial seat of the external soul. Although the above-mentioned title (which had ten holders, all related to the royal house, in the fourth, fifth and sixth dynasties) ceased to exist towards the end of the Old Kingdom, a standard representing the royal placenta was carried before the Pharaoh down to the time of the Ptolernies. Murx-.ry conjectures that the term “Opener” originated from some actual or forgotten ritual king-murder.

the bundle of life containing the placenta being ceremonislly opened at the conclusion of the reign.

The standard (Murray 8: Seligrnan) is here illustrated (Fig. 2 A, B). as are also bundles of life (Fig. 2 c-r).

Reverence for the placenta and umbilical cord is also noted in various African tribes (Roscoe). The whole subject is of interest as being a definite dreary, even if pre-scientific, about the nature of an easily observed biological phenomenon, namely the placenta.‘

Fig. 2: The Bundle ofljfr (Manny).

Ancient Egypt supplies the starting-point for another and prafounder train of thought which recurs constantly throughout the history of embryology, and to which I shall have to refer again more than once. This was concerned with the problem of deciding at what point the immortal constituent universally regarded as existing in living beings took up its residence in the embryo. Some fragments of ancient Indian philosophy assure us that the Vedic writers occupied themselves with

‘ To be compared with this preservntion of the placenta it the are taken in the disposal of the urnbihual and by primitive pwplm, includmg the early Greeks. Cook rhowu, with much detail (voL 2, pp. 169 E), that the stone called "Omphnlos,“ which wu 1 urlt-object It mlny ttfllples, upeeully that of Delphi, though exoter-ically mpposed to represent the navel or the earth (md in thin wry connected with a pillar luppomng the heavens), wu prob-bly also intended to mark the buriallate of the urnbilical card of the priest-lung, or perhaps of Zeus, Modem Greek elltlore. too, includes upecinl care: in the bestuwnl of the umbtlical cord. "Omphalos" ha bear the

Gubjtct of spec-ill monographs by Ratchet.

this question, and according to Crawley the Avesta theorises upon it. But as early as 1400 13.0., i.e. during the eighteenth dynasty in Egypt, something was said regarding this, for we have extant at the present day a very beautiful hymn to the sun-god, Aton, written by no less a person than Akhnaton (Nefer-kheperu-Ra Ua-en-Ra, 1:-,-3, 3_ gm hafghfng Amenhetep Neter heq Uast), generally known as {T ‘ff’;

Amenophis IV or the “heretie” king, who abandoned the traditional worship of the Theban god Amen-Ra and established an Aton-cult, as has been described by Baikie and others. One of his hymns, which bears considerable resemblance to the one hundred and fourth psalm, runs as follows (in Breasted's translation):

(The sun-god is addressed)

Creator of the germ in woman,

Maker of seed in man,

Giving life to the son in the body of his mother,

Soothing him that he may not weep,

Nurse (even) in the womb.

Giver of breath to animate every one that he malreth

When he cometh forth from the womb on the day of his birth.

Thou openest his mouth in speech, Thou supplies: his necessity.

When the fledgeling in the egg chirps in the shell Thou givest him breath therein to preserve him alive. When thou hast brought him together

To the paint of bursting out of the egg,

He cometh forth from the egg

To chirp with all his might.

He goeth about upon his two feet When he hath come forth therefrom.

Here no distinction is made between life and soul. At this early period there is no trace of the nations which appear later, such as the idea that embryos are not alive until the time of birth or hatching, or the idea that the soul is breathed into the embryo at some particular point in development. But in later times these considerations carried great weight, and

2] A msronr or £mmwoy_ocy

pith 31: rise of theology a definite stand had to be taken about them,

or o envise no etluul status could be assigned to abortion. Speculation on these matters has continued without cessation sincc the fimc of Alfilhfaggllybftfichlng 1! Climax perhaps in Christian times with Cangiaml 3 S ryalogm Sacra, and living on embedded in Roman Catholic theology up to our own era.‘ In the last century the subject seems to have . had a special fascination for Ernst H.-ieckel, who frequently mentioned it.‘ But the future holds no place for the discussion of such themes, and what has been called “theomgical embryology" is already dead, though we may perhaps descry its suwssor, psychological °ml"Y0l0KY. 11) such researches us those of Teuscher, Cesana, y Gonzalez, Swenson, Kuo Zing-Yang and CoghiIl.'

3. Artificial Incubation

The Egyptians were responsible for one of the greatest helps in systematic embryological study, namely the discovery of the artificial incubation of the egs of birds.‘ The success of this process was to have so obvious an effect on embryology, and the abortive attempts to bring it to completion were so frequent in the West right up to the nineteenth century AD.‘ that it is remarkable to find artificial incubation practised “probably," in Cadman’s words, “as far bad: as the dawn of the Old Kingdom, about 3000 11.0." It is doubtful whether the very remote date could be supported by Egyptologiml evidence; for, according to Hall and Lowe, hens were not introduced into Egypt from Mesopotamia or India until the time of the eighteenth dynasty (ca. 1400 n.c.) when there was much interoourse with the East (of. Queen Tiy and the Tel—elAmarna correspondence): before then the Egyptians had only goose or duck eggs. Artificial incubation is certainly as old as Diodorus Siculus and Pliny, forboth of them refer to the practice, the latter in connection with a curious piece of ancient sympathetic magic.

x 5,, 5,15,,‘ pP_ 55.6, 7é:u_d za , also the interesting note or Vorwabl. Here might also be meminncd the pro army 2 embryos (aborted or of other _nng1n) were used in lntiquity as lubstitutca for human saazfioe. The litcnmre on this -an be ruched through the then dtsutsston at Pminguyn. r. 294. who mention: the hub-ml bum! at romses under glus—furnxr:es in his tmmxy or :h_aru4:l technology. More recently the subject has been thoroughly investigated by Elnade, pp. 75 E.

-E;-arm.» oflllm. voL 1, p. 355;R1dd1¢ cf the Ur-«rem. dz 8.

' The large mass of modern work on the psycho-ueunl. deveio men; of the foetus has been brought together in admirable monographs by Carrru cl: Detwiler, and Gesell 3: Amntruda. The great Classic on physiological unbryology is of eon:-re the book §§3‘g,’IP1-eyvfilr ign 133;, mu} 1: was this wh‘::e‘h sumuhtcd the present writer to produce

' mi mlnyoi -an yurs er. ,

‘An excellent ium°§’or"u7e technique to in culture: has rtcmtly been written by Landauer.

' Cf. pp. 10: if.

Livia Augusta, the Empresse [says Pliny]. wife sometime of Nero, when she was conceived by him and went with that child (who afterwards proved to be Tiberius Caesar) being very desirous (like a young fine lady as she was) to have a jolly boy, practised this girlish experiment to forelrnow what she should have in the end; she make an egge, and ever carried it about her in herwarme bosorme: and ifatanytirneshehad ocrarsionto layit away, she would convey it closely out of her own warrne lap into her nurses for fesre it shnuldcl'u'll.Andwr-ilythispresageprovedtrue, theeggeberzrneacoclre chicken, and she was delivered of a sonne. And hereof it maywellbecarne the device oflate, to lay eges in some wanneplaoe and tomakeasoftfire underneath of small straw or light chafie to give a lrinde of moderate hate; but evennore the egges must be turned with a mans or womans hand, both night and day, and so at the set time they looked for r-hirzkens andhad them.‘

Pliny also says:

Over and hesidm there be some egs that will come to he birds without sitting of the hcnne, even by the wozke of Nature onely, as a man may see the experience in the dunghills of Egypt. There goeth a pretty jeast of a notable drunhrd of Syracuse, whrse manner was when hee went into the Taverne todrinketolaycertaineeggesintheearth, and cover them with moulde, andhe would notrisenorgiveover hihhing nntill theywerehatched. To conclude, a man or a woman may hatch eggcs with the very hate onely of their body.

This story occurs also in Aristotle.

The Emperor Hadriarr——crm'au'latum vmm'um zzploralor, as Tertulliau urlls h.irn—writing from Egypt in Am. 130 to his brother-in-law, L. Julius Servianus, says, “I wish them no worse than that they should feed on their own chickens, and how foully they hatch them, I am ashamed to tell you."' In the Dnaiplion dz l'Eg}j>te, written by the members of the scientific staff of Napoleon's Egyptian expedition, and published at Paris in X809, Rotiere an Rouyer wrote on the artificial incubation of the Egyptians.‘ They conjecture very probably that Hadrian was shocked owing to a misunderstanding shared by Aristotle, Pliny, dc Pauw‘ and de Rhumur, namely that the gzlleh or dung was used to hat the eggs by its fermentation, and not, as is and was actually the use. by being slowly burnt in the incubation ovens. Bay gave an account of the ovens in modern times, but the best one is that of Lane, written in I836:

The Egyptians have long been famous for hatching fowls’ eggs by artifidal heat. This practice, though obscurely described by ancient authors, appears to

' Philemon Holland‘ n-nnlariou. ' Gregorovius, p. 124. 'VnL r.r>.:w3. I ‘Vol. no. 2114.

have become common in ancient Egypt from an early time. In Upper E t there are over fifty establishments, and in Lower Egypt more than a hundgizii The furnace is constructed of sundried bricks and consists of two paxaflgl rows of small ovens and cells for fire divided by ii narrow vaulted

each even being about 9 or re feet long, 8 feet wide and 5 or 6 feet high, and having above it it vaulted fire—ccll of the same size but rather loss in height. The eggs are placed upon mats or straw, one tier above another usually to the number of three tiers and the burning fuel is placed upon the floors of the fire«cells above. The entrance of the furnace is well closed. Each furnace consists of from twelve to 24 ovens and receives about i5o,ooo eggs during the annual period of its continuing open, one quarter or one third of which generally fall. The peasants supply the eggs and the attendants examine them and aiterivrirds generally give one chiclten for every two eggs that they have received. The general heat maintained during the processisfrum too to 103“ of Fahrenheit‘: thermometer. The nxinager, having been accustomed to the art from his youth, knows from long experience the exrict temperature that is required for the success of the operation without having any instrument like our thermometer to guide himr The eggs hatch after exactly the same period as in the case of natural incubation. I have not found that the {owls produced in this manner are inferior in point of flavour or in other respects to those produced from the egg in the ordinary way.‘

Plate In (opposite), taken from Cadmzin, shows the interior of a modem peas:int's incubator. There is reason to believe that its construction and operation vary very little, if at all, from that of the ovens used in dynastic Egypt.

When Baf visited the rustic incubators in 1912 he took with him a flask of lime water and a thermometer. The former showed a large precipitation of calcium carbonate and the latter stood at 4o” C. He was led to speculate on the value of a high CO, tension in the atmosphere, and concluded that it must have a beneficial effect, since the loss in the traditional incubator was not more than 4 per cent., while that in the oilheated agricultural incubators of his time was as much as 40 per cent. Cadmarr, writing in 1921, suggests that the well~lmown non-sitting instinct of Egyptian poultry is an effect of the ancient pmctioe oi artificial incubation. But enough has been said of the Egyptian Ma'ntaI at-katokect, or chiclten factories. In spite of the rernzirkable opportunity thus afforded for acquiring facts in experimental embryology, no use was apparently ever made of it, though there seems to be a certain amount of traditional information current among the peasant operators, as, for example, that the nil; or life enters mto_the egg at the eleverith day. It would be interesting to investigate this aspect of the subject


Illannen and Curwwu, p. 287. 14 PLATE 1

(B) Clzinue peasant inmbaloy (from Kmg).

In China also it would appear that artificial incubation was successfully carried on in antiquity, if we may judge by the account given by King.‘ Incubation in China is carried on in wicker baskets, heated with charcoal pans (Plate 13, facing page 24). The attendants sleep in the incubator itself, and use the same thennox-neter as the Egyptians, namely their eyelids, to which they apply the blunt end of the egg. The Egyptian success was known generally in the West in later times, though it could not be imitated. “The Aegyptians,” said Sir Thomas Browne, “observed a better way to hatch their Eggs in Ovens, than the Babylonians to roast them at the bottom of a sling, by swinging them round about, till heat from motion had concocted them; for that confuseth all parts without any such eflect.” Browne's slightly rueful tone suggests that he tried it himself. It is interesting that this quaint experiment was the cause of a controversy between Sarsi, who asserted on the authority of Suidas that it was possible, and Galileo, who thought the idea ridiculous.‘ Modern work on the instability of albumen solutions, such as that of Harris, lends some colour to the legend.‘

4. Indian Antiquity

Ancient Indian embryology achieved a relatively high level. Structures such as the amniotic membrane are referred to in the Bhagavm10:75.‘ The Sum/to-samhita says‘ that the embryo is formed of a mixture of semen and blood,‘ both of which originate from chyle’. In the third month commences the dilferentiation into the various parts of the body, legs, arms and head; in the fourth follows the distinct development of the thorax, abdomen and heart; in the sixth are developed hair, nails, bones, sinews and veins; and in the seventh month the embryo is furnished with any other things that may be necessary for it. In the eighth there is a drawing of the vital-force (ojus) to and from mother and embryo, which explains why the foetus is not yet viable.’ The hard parts of the body are derived from the father, the soft from the mother. Nourishment is oarriedonthxoughvessels whiehleadchyle frornmother to foetus.‘

The outstanding work on Indian embryology is now that of Dasgupta, who in his chapter “Speculations in the medical schools" deals with the /lyur veda, that great body of medical texts extending over more than

‘Farmer: . . . p. 157. ' Fm-rrrmenti e Lellerr, p. 66.

' See Needharn (r931). 13. 275. ‘ Ca. and century n.c.

‘The oldest pans of this eorpu: are now oonsidered to date from the am two or

three centuries 4.1:.

' As we Ihflll see, this is I very Greek idea.

1 Perhaps this is comparable with the Hippocratic llxeiv.

' For further details, ree Vullen and Essex.

t\_venty centuries in its composition. Both the Allmrva vain and the Ayur cede deal with the curing of disease, but the former only by means of magic and incantations.

The factors going to the production of the foetus were (a) the father's semen, (b) the mother’s blood (iozrita), (c) the dtman, or subtle body, (11) the manor or mind, united to a particular embryo by reason of its karma. The subtle body consisted of tire, earth, air and water in the proper proportions. On these elements the Buddhist writers laid especial stress, adding to them two more, the principle of knowledge (mjixfina-dha31u)md the sernen—'olood substratum mentioned above, and thus obtaining the six constituents (;ozn_r:iy_rr ifinfitiinfign rnmavfiyzit). Elsewhere the blood in question is spetifitzally referred to as menstrual (firiava), both by Susrutzt and Caraka. This is of great interest in View of the Aristotelian doctrine described on pp. 42-3 ofthc present work, which it precisely resembles. The theory may, of course, have arisen quite independently in Greece and India, but it is perhaps more likely to have passed in one direction or the other, in which direction it is hard to say (of. also the cheese analogy discussed on p. 5a).

In this connection it is of interest that, according to s:up».~s,x the Hindu theologians considered it a crime for a girl to menstruatc before going to her husband's house from her l'ather’s. Webb, in his Pothologica Indira, expressly states‘ that the regrettable institution of child marriage (cf. Rathbone) originated from the belief that the menstrual blood was the nmteria prima of the embryo and that to lose any before the first entry of sperm amounted to child murder. “If an unmarried girl has the menstnral secretion in her father's house, he incurs a guilt equal to the destruction of the foetus."\Vas it a mere chance that thisinterpretadon of Aristotelian doctrine did not occur to the “fest? Other semi~superstitious beliefs about the catamenia oeminlyfiourishcd there. as Crawfurd, Feis and others show.

palhana, writing about /co. rloo, says: in the firs: month the foetus has a jcllylike form (kalakz), ‘m the second month, the material constitucm; of the body having undergone a chemical change (abhz}>rapzuyamine) due to the action of cold, heat and air (echo of Hippocratmi), the foetus becomes hard (glumu). Difiierentialion of limbs takes place in the third and fourth months, the appearance of oorisciottsness and intelligence later. The controversies in the West about the priority of appeamnce of the limbs and organs (see pp. 28 5.) have apparmtly their exact, and equally barren, counterpart in India. Thus the head appears

fizst, according to Kumirasirasnnd Saunaka; tllc hmfi. =C°°Yd1“3 "3 Krtzvirya; the navel, according to P-iriénra; etc.. etc! Contraception, p. 256. 'PP259. 273-

The comparison of the formation of the embryo with due clotting of rnilkinto chese, first noted in Aristotle (see pp. 50, 84-5), occurs also in Indian embryology. The Sulruta-sargrhita says that as the semen and blood undergo chemical changes through heat, seven: different layers of skin (kalfi) are formed, like the creamy layers (runtfittzhi) fanned in milk. This concept occurs again in a Sfitra on embryology originally written in Sanskrit, translated into Chinese (first MS. A.!). 1104), and now into German by I-Ifihotter. "Development, 0 Ananda," Buddha is made to say, “is comparable to a vessel of milk, like as this fetments and forms a kind of Ieefir or cheese." The rest of this text contains an account of the harmonious collaboration of many factors (“winds" with dilferent names; a typically Buddhist characteristic) in the formation of the foetus.‘

In which direction did all these theories travel along the GraecoIndian line of communication?

5. Hellenic Antiquity; the Pre-Soctaticsl

Ancient Greek thought shows many evidences of appreciation of the mystery of embryonic growth, as for example in the Orphic cosmogo— nies, which had their origin about the seventh or eighth century n.c. In these religious and legendary descriptions of the world, which have been exhaustively discussed by A. B. Cool: and F. Lukas, the cosmic egg playsalargepamandhasbeenshowntooceuralsointheancient ensmogonies of Egypt, India, Persia and Phoenicia (see Fig. 3, page 21). Afamiliarreferenoe to this cosmic egg,‘ out of which all things were produced at the beginning of the world, is in Aristophanes’ comedy The Birds, where the owl, as leader of the Chorus, says in the Parahasis (Sir John Sheppard's translation):

Chaos was first, and Night, and the darkness of Emptiness, gloom Iartarmn, vast;

Earth was not, nor Haven, nor Air, but only the bosom of Darkness; and there with a stirring at last

‘ Hunrnnt and I. I-‘isdrer hxve Issanhled some material daling with ancient Indian Mm on heredity.

‘In the mining sequence ofrectiom, the rnarerial is treated, as throughout this hook, ehrnnologially. Balm (15736), however, give: a valuable summary of embryology lmm the pre—Soentxa to Galen Inclusive, In-rnged under sulrju1~hnding:. So also does A. VV. Meyer (run).

'P¢rh1prIlnutlicrrcferenuetolheplaceoflheegginuuientcnsrllogonyocurrs in fliedrnbim Niglur, where Aladdin’: request for a roe’! egg is naked as n blasphemy B1 thegutive. Inthevisitvnn nISl Hrld¢garr!,ttvo(seean.p. 3-}).ihecusn-tieeggnppeaos,

InLiebesc_IIfltz.Andtheten:cityofhl'eol'IhunmimrrIIaybcglugedlmm thefnettlutc. Fmmerutheu-irlonlzeeightzmth century,lud C. H. Rio-:(inP:ych:, I929!) entertained in It also influenced utly theories ufmineral formation (Adams).

Of wings, though the wings were of darkness too, black Night was inspired ti wind-egg‘ to lay,

And from that, with the turn of the seasons, there sprang to the light the Desired,

Love, and his wings were of gold, and his spirit as swift as the wind when it blows every way.

Love moved in the Emptiness vast, Love mingled with Chaos, in spite of the darkness of Night,

Engenclering us, and he brought us at List to the light.

The pre-Socratic philosophers nearly all seem to have had opinions upon embryolegical phenomena, many of which are worth referring to.‘ These investigators of nature who lived in Greece from the eighth century onwards are only known to us through the writin gs of others, or in some cases in the form of fragments, for all their Complete books have perished. Diels' collection of the Fragment: der Van-oleralilirr is the most convenient source for what is left, but the assembling of their opinions has not been left to modern times, for a collection of them occurs in the writings of Plutarch of Chaeronea4(3rd century A.D.). It is necessary to make use of some caution in dmcrihing their views, for Aristotle, as an instance. frequently gives the most un.f:iir versions of the views of his predecessors. The account which follows is based upon Plutarch, in Philemon Holland's translation,‘ and Diels. Empedocles of Acragns, who lived about 444 B.C., believed that "the embryo derives its composition out of vessels that are four in number, two veins and two arteries, through which blood is brought to the embryo." He also held that the sinews are formed from a mixture of equal parts of earth and air, that the nails are water congealed, and that the bones are formed from n mixture of equal parts of water and earth. Sweat and tears, on the other hand, are made up of four parts of fire to one of water. Empedocles also had opinions about the origin of monsters’ and twins,

‘ infertile eggs were commonly called "wind-eggs" in antiquity (see below. PPS: and 67121. The rmnan of nnu-nah being unpregnxted by the wind has been mvflflgiltd by Z}! c.

'5 th recenrino ogni hhyixslry. _ ’ Itei: ndw certnin that tiiis collection is not by Plutzmh himself but by an mriier

compiler, Aetios (tee Bumet). '11:: rmhryologieal material it in Bk. v of Dr Phzcilig.

‘ In certain cases, Holler-id’: translation (rboj) has been modified so I: to make it agree with mew rm. My thanks in due to Mr H. C. Baldry In connection writ, urn.

‘ As this IS the firs! mention made so far ofmonrtt-rs, 1 rnay_t.1le the orppominiry ol remarking that spin from cursory rtfertnce: from time to tune (see bclowne g. pp. Br, 83, X0), in, :78, x94, mi. gin end us), the riinifioatwni or the history at‘ zeruology have not here been terimuly pursuedi The mariogr-iph:_ of Ballnnryw-ie, Dzreste and C. 1S. Thmnpson contain much nmrerial on this subiect. Ballanryne point: out that perhaps the oldest explanation of them was that the gods were playing, IS in the phrase attributed to Hmclirui, Zn); 514361. heruge “lusus n_i-itiii-re." "Nimriprei," Ind our own “sport " He also cansidtn the relimon of Ir-icirnt trmtnlogy to nugury, and figure: In interesting Chzldezri ternroscapie tablet. In later ti'i-nes the and asserted that the influence of the maternal imagination upon the embryo was so great that its formation could be guided and interfered with.‘

Empedoclee [says Plutarch] saith that men begin to take forme after the thirtie-first day and are finished and knit in their parts within 50 daies wanting one. Asclepiades saith that the members of males because they are more hot are joynted and receive shape in the space of 26 daies, and many of them sooner, but are finished and complet in all limbes within 50 daics but females require two moneths ere they be fashioned, and fewer before they come to their perfection, for that they want naturall hwt. As for the parts of unreasonable creatures they come to their accomplishment sooner or later, according to the temperature of their elements. . Empedocles alloweth it to be a creature animall, howbeit that it hath no breath within the bellie, mary the first time that it hath respiration is at the birth, namely, when the superfluous huxniditie which is in such unborne fruits is retired and gone, so that the aire from without cntreth into the void vessels lying open.

Anaxagoras of Clazomenae (500-4,28 B.C.) may have said that the milk of mammals corresponded to the white of the {owl's egg, but that observation is also attributed to Alcmaeun of Crotona. It is more certain that he spoke of a fire inside the embryo which set the parts in order as it developed, and that the head was the part to he formed first in development. This thesiswas supported by Alcmaeon, and by Hippo of Samos, a Pythagorean, in the fifth century n.c., but Diogenes of Apollonia maintained about the same time that a mass of flesh was formed first, and afterwards the bones and nerves were differentiated. Plutarch remarks about this: “Alt,-rnaeon affirmeth that the head is first made as being ‘the seat of reason. Physicians will have the hart to be the first, wherein theveincs and arteries are. Some thinke the great toe is framed first, others the navill.“

application at‘ the Aristotelian system of calsation to monsters gave occasion for much waste of human ingenuity, as m the treatises of Schott (r662) and Licetus (x616). where all four causes have to operate on three levels, divine, natural Ind diaboliml. In 1578 Michel de Montaigne took a very modern view of terata, as described by Debrunner. An embryologist and an art historian in pnrsbiosis, no to say, have written an interesting introduction to the subject (Hamburger 5.:Born).

Scharz has gone about to prove, not unconvincingly, that much of mythology arose (tom the cbsewatimx oi developmental sbvrwmxalrtiu. Thus it cyclaops foetus may have suggested Polyphemus, I sy-mpodial one Siren, and I diprosopous one Janus. The idea of Centaur may have originated Erom a hydrocephnlie calf, and the Gorgon head from an ncormic placental parasite. Occipitatl enoephalocoele would have produced Atlas, foetal exomphalos Prometheus, and nchondroplasia Egyptian Ftah. The likelihood of these sum-rises increases on careful consideration. Ci. Science and Ciciliralion in China, vol. 3, for parallel Asian data.

When vrsitmg the famous Buddhist cave-temples at Tunhuang, Kamu, in China, in 1943 I observed several frescoes of guardian deities (lahapdla) with arm: coming forth from their eyes, and bearing distal eyes on the palms of these supernumenry limbs (Plat: II, facing page 30). lt occurred to me to wonder whether some monk pacing the seashore had chanced upon a rpontaneau: example of heternmorphoris in a crustacean. These Ionm commonly regenerate In eye-stalk instead of an antenna, or an Interuu instead of a limb.

I See below, p. :15.

The othet contributions of Diogenes to this primitive embryology were the rewgnition of the placenta as an organ of foetal nutrition, and the view that the male embryo “as formed in four months but the female not till five months had elapsed—-a notion similar to that found in Asclepiades and Empedocles, as we have seen. He also associated heat with the generation of little animals out of slime, and compared this with the hut of the uterus. He considered that the embryo was not alive. “Diogenes saith that infants are bred within the matrioe inanimate, hmvbeit in heat, whereupon it comrneth that the inborn hat, so soon as ever the infant is turned out of the mothefs wombe, draweth the cold into the lungs!" But the principal pre-Socratic embryologist was, as Zeller points out,’ Alcmacon of Crotona. who lived in the sixth century n.c., a disciple of Pythagoras, though apparently an independensmze. Heissnidtnhavehecn the first manta make fngmmts of Alcmaeon (not to be confused with Alcxnan, the Laced.»manian poet) have been collected together by Wachtler; the most important are xxx and xxx. Athenaeus in the Dtfpnosvpliflt 3333. in his usual chattyway, “Now with respect to eggs Anaxngbras in his 170011 0!! natural philosophy says that what is called the milk of the bird is the white which is in the eggs." This may be a wrong ascriptian; it MY refer to Alanaeon, for Aristotle says in his book on the generation of animals,’

Nature not only places the material of the creature in the egg but also nourishment suflicicnt for its growth. for since :11: mother-bird tzmnot PW‘ ted the young within herself she produces the nourishment in the £83 "l°"l§ with it. Whereas the nourishment which is called milk is produced for the young of viripar: in another part, in the brusts, N321!-rt docs this [Or birth in the egg. The opposite, hon ever, is the case to what p€0Pl¢ ‘kink and W53‘ is asserted byAlcma:on of Cmtona. For it is not the white that is 111: milhbul the yolk, for it is this that is the nourishment of lht Chkliq “lit”?-‘ ‘hi’? think it is the white because of the similarity of the C010!“-

Whether Aristotle was led to this conclusion because 05 1355 =r|’°f1¢°\!5 ides about the part played in foetal nutrition by yolk and white rcspectirely orwlmher he recognised :1 similarity between yolk ynd mflk on account oftheir fatty nature, we cannot 1:11. In any case. {us cm-rec~ ticn ofAlanaean was in the right direction; and the 00mP11'15°Il Of '-h¢

Anflthu unaidation of Holland ha: been necesnry here for the reason rim on


Htlflomarpllaxfx in a gunman dmy (lokapala) dzpimd m u frnto on M: rm" :2] one nf lht mcz-temple: at Ch'i:n-Fa-Ting,-, Tunlmang. Kanm pmcincr, China. (Original photograph. I943.)

aminovacid distribution in the two phosphoproteins, the casein of milk and the vitellin of yolk (Abderhalden 8: Hunta) shows their similarity. Parmenids asserted a connection between male embryos and the right side of the body and between female embryos and the left side of the hody—an idea which, considering its total lack of foundation, had a very long lease of life in the world of thoughts There was much controversy an the question of how foetal nutrition went on; the atomists, Dernocritus (born about 460 a.c.) and Epicurus (born about 342 n.c.), said that the embryo ate and drank per or. “Democritus and Epicurus hold,” says Plutarch, “that this Imperfect fruit of the womb receiwth nourishmmt at the mouth; and thereupon it cometh that so soon as ever it is borne it seeketh and nuzzeleth with the mouth for the hrest head or nipple of the pappe: for that within the matrice there be certain teats; yea, and mouths too, whereby they may be nourished. But Alcmaeon afiinneth that the infant within the mother’s wombe, feedeth by the whole body throughout for that it sucketh to it and draweth in maner of a spunge, of all the food, that which is good for nourishment." It would appear also that Democritus believed the external form of the embryo to be developed before the internal organs were formed.

6. Hippocratic Embryology and the Doctrine of the Two Seeds

But the foregoing fragments of speculatioifdo not really amount to much. The first detailed and clear-cut body ofembryologiml knowledge is associated with the name of Hippocrates, of whom nothing certain is known saw that he was born probably in the forty-fifth Olympiad, about 4.60 n.c., that he lived on the island of Cos in the Aegean Sea, and that he acquired grater fame as a physician than any of his predecessors, if we may except the legendary names of Aesculapius, Machaon and Podalirios. It has not been believed for many centuria past that all the writings in the collection of Hippocratic boolts were actually set down by him, and much discussion has taken place about the authenticity of individual documents.

Most of the emhryological information is contained in a section which in other respects (style, etc.) shows homogeneity. We are therefore rather interested in the unknown biological thinker who wrote the books in this class, for he could with considerable justice be referred to as the first emhryologist. Littré dismisses his identity, but there is no good evidence for any of the theories about it, though perhaps the most likely one is that he was Polybus, the son-in-law of Hippocrates. That the

‘11msitoeurnuoneoItheIewideasoonuinedintheCaHiponEaof(HIudiIn Ouillcmywhichnnthzoughmsuyedifionsintheeightnenthccntury.

3! A ursroxr or rznnnronoor

Wr1tl!1_gs on generation are only slightly later than the time of Hippocrates is more or less clear from the {act that Bacchius knew of them and actually mentions them. ’

For the most part the embryological knowledge of Hlppocmta is concerned with obstetrical and gynaecological problems.‘ Thus in me AP’""im=» d¢aew;mI. the books on cpidemixs, fflllhullal. the trmtise °“ an nature 0! “'°m¢n: mg! yovatxelqg‘ nfiéatog, the discussions of Plemat‘-"C biflih 3691 l5‘K1d[47iI'ov, the books on the diseases of women. -7522 7'~"'l1"€€[IIWy and the pamphlet on superfoetation. there are many facts recorded about the embryo, but all with obstetrical reference. There are some curious notions to be found there, such as the association if rtifltfnd left breasts with twin embryos and a prognostic dependent

In .

But the three books which are most irnportant in the history of embryology are the treatise on Regimen, mg) am/mg, the nor]; an generation. negl yawicu and the book about the nature of the infant, 71:92 Marc; mzzdfov. The two latter really form one continuous discussion, and it is not at all clear how they came to be split up into separate books. In the Regimen the writer expound: his fundamental physiological ideas, involving the two main constituents of all natural bodies, fire and water. Each of these is made up of three primary natures, only separable in thought and never found isolated, heat, dryness and moisture, and each of them has the power of attracting (way) their like, an important feature of the system. Life consists in moisture being dried up by fire and fire being wetted by moisture alternately; ‘rgoqitf, the nourishment (moisture) coming into the body. is consumed by the {ire so that fresh -rga¢y' is in its turn required.

It is important to note that the Hippocratic school was far more akin in its general attitude to living things to modern physiology" than the Aristotelian and Galenic physiology. For no considerations of final muses complicate the causal explanations of the Hippocratic school, and the author of the negl duu"rr]; indeed devotes seven chapters to a detailed comparison of the processes of the body (1) with the processes of the inorganic world both celestial and terrestrial. and (b) with the processes used by men in the arts and crafts, such as iron-workers, Cobblers, ezrpenters and confcctioners. These discussions present strongly mechanistic features.

1 The treatises On Semen and Or: we Development ofllne chad have rccentli been

trmsl tedb nu . _ ' Séecial of the opinions in the Hippocntic mipm on heredity will be found in Johannren und Hornrnel, and an scientific methodology in S_enn. And In Demos-nrein physiology. “'ell.mann rm discussed the relation between the pre~Secs-uric ntamists and the Hippocratic carpal.

He then in Section 9 sets forth his theory of the formation of the embryo.

Whatever may be the sex which chance gives to the embryo, it is set in motion, being humid, by tire, and thus it extracts its nourishment from the food and breath introduced into the mother. First of all this attraction is the same throughout because the body is porous but by the motion and the fire it dries up and solidifies (6:-rd 6:! tr]; xmiatur; xal 1Dl71flJQdC Engal:-era: atal a-‘repeat?-rat); as it solidifies, a dense outer crust is formed, and then the fire inside cannot any more draw in sufficient nourishment and dam not expel the air because of the density of the surrounding surface. It therefore consumes the interior humidity. In this way parts naturally solid being up to 2 point hard and dry are not consumed to feed the fire but fortify and condense themselves the more the humidity disappears—these are called bona and nerves. The fire burns up the mixed humidity and forwards development towards the natural disposition of the body in this manner; through the solid and dry parts it cannot make permanent channels but it can do so through the soft wet parts, for these are all nourishment to it. There is also in these parts a certain dryness which the fire does not consume, and they become compacted one to another. Therefore the most interior fire, being closed round on all sides, becomes the most abundant and makes the most canals for itself (for that was the wettest part) and this is called the belly. issuing out from thence, and finding no nourishment outside, it makes the air pipes and those for conducting and distributing food. As for the enclosed fire, it makes three circulations in the body and what were the most humid parts become the venue came. In the intermediate part the remainder of the water contracts and hardens forming the flesh.

In this account of the formation of the embryo, which seems at first sight a little fantastic, there are several interesting things to be remarked. Firstly, there is to be noted throughout it a remarkable attempt at causal explanations and not simply morphological description. The Hippocratic writer is out to explain the development of the embryo from the very beginning on machine-like principles, no doubt unduly simplified. but related directly to the observed properties of fire and water. In this way he is the spiritual ancestor of Gassendi and Descartes. The second point of interest is that he speaks of the embryo drying up during its development, a piece of observation which anyone could make by comparing a fourth-day chick with a fourteenth-day one, but which we expras today in graphical form.‘ Thirdly, the ascription of the main driving force in development to fire has doubtless no direct relation to John Mayotv’s discovery,’ two thousand years later, that there is a similarity between R burning candle and a living mouse each in its bell-jar, and may mean as much or as little :3 Sir Thomas Browne's remark,‘ “Life is a pure flame, and we live by an invisible sun within us." Yet the essential chemical aspect of living matter is oxidation, and the development of the embryo no less than the life of the adult is subject to this rule, so that what may have been a mere guess on the part of the Hippocratic writer may also have been a flash of insight due to the simple observation which, after all, it was always possible to make, namely, that both fires and living things could be msily stifled.

‘ The wntzr-context! of the chick embryo drops from 95 per cent. at the fifth day to So‘;-)2, gent. at batching. See Fig, 4. 1 72.

Water-content of‘ chick embryo


Preformationism is perhaps foreshadowed in Section 26 of the same treatise.

Everything in the embryo is [armed simultaneously. All the limbs separate themselves at the some time and so grow, none comes before or after other, but those which are naturally bigger appear before the smaller, without being formed earlier. Not all embryos form themselves in an equal time but some earlier and some later according to whether (ht! meet with fir: 3115

food. some have everything visible in 40 days, others in 2 months, 3, or 4. They also become visible at variable times and show themselves to the light having the blend (of fire and water) wbidr they always will have.

The work on Generation is equally interesting. The arlier sections deal with the differences between the male and female seed, and the latter is identified with the vaginal secretion.‘ Purely embryological discussion at. Section :4, where it is stated that the embryo is nourished by maternal blood, which flows to the foetus and there eoagulatcs, forming the embryonic flesh. The proof alleged for this is that during pregnancy the flow of rnenstmal blood ceases; therefore it must be used up on the way out.‘ In Secfion K5 the umbilical cord is recognised as the means by which foetal respiration is carried on. Section 17 contains a fine description of development with a very interesting analogy. “The flesh," it is said. "brought together by the breath (16 m-efipa) grows and divides itself into members, like going to like, dense to dense, flabby to flabby, humid to humid. The bones harden, eoagulated by the hu: ” Then a demonstration arperiment follows:

Attach a tube to an earthen vessel, introduce through it some earth, sand, and lead chips, then pour in some water and blow through the tube. First of all, everythingwillbemixedup,butafreraeertaintimetlreludwillgoto thelead,thesandtodresand, andtheearthtotbeearth,a.ndifthewaterl>c allowedto dryup and thevssel bebroken, itwill beseenthatthisisso. In the same way seed and flesh articulate themselves. I shall say no more on this point.

Here again was an attanpt at causal explanation, rather than morphological description.

Section 22 contains a suggrstive comparison between seeds of plants and embryos of animals, but the identification of stalk with umbilical and leads to a certain confusion. Perhaps the most interesting passage of all is to be found in Section 29.

Now I shall speak [says the unknown Hippocratic embrynlogist] of the elraractuswintliipmndsedaboveto discunmdwhichslrnwasdarlya human intelligence an to anyone who will examine these things that the seed is in amt-mbrane, that the umbilicus occupies the middle of it, that it alternately draws the airthruugh itself and then expelsit, and that the membersare attached to the umbilicus. In a word, all the constitution of the foetus u I

‘This doctrine of the two needs, reinforeed by Epiurrun support. competed for many eem-rrn'es with the Aristotelian doctrine that only the male enntrflnrred ucd whilethe fa-nale provided blood (:1. .39-4e,43,belmr). In lflutbegrtatrnorphologist Wilhdmflis uwthe impmtnweof ' neculareoritrmuuyforthelaiamrynfbiology andaknehediudereloprnerrtinnninterrstingpapentoolirdehown.

"Fhiswu lheeueneeofArixtotle’: doetnne, nee b:low,prp.qzH.

have described it to you, you will find fmrn one end to the other if you will use the following proof. Take 20 eggs or more and give them to 2 or 3 hens to incubate, then each day from the second om:-ards till the time of hatching

take out an egg, break it, and examine it. You will find everything as I say so far as ‘A bird ram resemble a man. He who has not made these observations before will be amazed to find an umbilicus in a bird's egg. But these things are so, and this is “hat I intended to say about them.

We see here as clearly as possible the beginnings of systematic embryological knowledge. and from this point onwards, through Aristotle, Leonardo, Harvey and von Baer, to the current number ofthc Archie]. Entu-icklungrmechanilz, the line runs as straight as Watling Street.

In Section 30 there is an important passage in which the author dis« cusses the phenomena of birth.

I say that it is the lack of food which leads to birth, unless any violence has been done; the proof of which is this—the hirdis formed thus from the yolk of the eg, the egg gets hot under the sitting hen and that which is inside is put into movement. Heated, that which is inside begins to have breath and draws by countersattraction another oold breath coming from the outside air and traversing the eg, for the egg is soft enough to allow :1 sufficient quantity of respiration to penetrate to the contents. The bird grows inside the egg and articulates itself exactly like the child as I have previously described. It comes from the yolk but it has its food from and its growth in, the white. To convince oneself of this it is only necessary to observe it attentively. When there is no more food for the young one in the egg and it has nothing on which to live, it makes violent movements, searches for food, and breaks the membrsnes. The mother, perceiving that the embryo is vigorously moving. smashes the shell. This occurs after 2o days. It is evident that this is how thinga happen for when the mother breaks the shell there is only an insignifi< cant quantity of liquid in it. All has been consumed by the foetus. In just the same way, when the child has grown big and the mother cannot continue to provide him with enough nourishment, he becomes agitated, breaks through the membranes and incontinently passes out into the external world free from any bonds. In the some way among beasts and savage animals birth occurs at a time fixed for each species without overshooting it, for necessarily in each case there must be a point at which intraauterine nourishment will become inadequate. Those which have least food for the foetus come quickest to birth and rice onrd. That is all that I had to any upon this subject.

The theory underlying this passage evidently is that the main food of the fowl embryo is the white and that the yolk is there purely for constructional purposes. Had the author not been strongly attached to this erroneous view he could not have failed to notice the unabsorbed yolk-sac which still protrudes from the abdomen of the hatching chick, and if he had given this fact a little more prominence he could hardly have come to enunciate the general theory of birth which appears in the above passage.‘ Moreover, had he been acquainted with the circulation of the matemal and foetal blood in viviparous animals, he could hardly have held that there was less food in a given amount of maternal blood at the end of development than at the beginning. But his attempted theory of birth was a worthy piece of scientific thinking, and we cannot yet be said. to understand the principles governing incubation time.‘

The treatises on food and on flesh 2-zegl -rgoqiijg and .-reg! aaezcinr (ca. 400 3.0.) contain points of embryological interest. Section 30 of the former contains some remarks on embryonic respiration, and Section 3 of the latter has a theory of the formation of nerves, bones, etc., by diflerences in composition of glutinous substances, fats, water, etc. Section 6 supports the view that the embryo is nourished in ulna by sucking blood from the placenta, and the proof given is that its intestine contains the meconium at birth. Moreover, it is argued, if this were not so, how could the embryo know how to suck after it is born?

7. Aristotle's great Systematisation

After the Hippocratic writings nothing is of importance for our subject till Aristotle. It is true that in the Timaeu: Plato deals with natural phenomena, eclectically adopting opinions from many previous writers and welding them into a not very harmonious or logical whole. But he has hardly any observations about the development of the embryo. The four elcments——earth, fire, air and water—-are, according to him, all bodies; and therefore have plane surfaces which are composed of triangles. Applying this semi-atomic hypothesis to the growth of the young animal, he says,

The frame of the entire creature when young has the triangles of each kind new and may be compared to the lrecl of a vessel that is just off the stocks; they are locked firmly together and yet the whole mass is soft and delicate, being freshly formed of marrow and nurtured on milk. Now when the tnio-rgl'csaw:m"mh’\a‘r moresazrrd ri'rr'ml':.n-e cvrrrposedcvmeirr from zvialiocrt, and are comprehended in the body, being older and weaker than the triangles already there, the frame of the body gets the better of them and its newer triangles cut them up and so the animal grows great, being nourished by a multitude of Slflulaf particles.

‘ In connection with the views of the Hippocratic embryologist on the exhaustion of nutrimcnl u the muse of birth. it is of interest that modern research is pointing to n probnbl: failure or inefliciency of the mlfnmlllfln placenta towards the and of inmuterine life. The well-known increase of erythrocytes, haemoglobin, blood-volume, etc , in the foetus or the end of pregnancy. together with I shift of the dls!0Cllltoncurve of foeul blood, may be reaction: adaptive to a relative Inouemia caused by placental inefficiency, and comparable with those found at high altitude. See the monognphs of Bnrcruft and the ohort survey of Needham (X933).

Ct. Needham (lggr) and Nice.

This is as near as Plato gets to embryological speculation. His description has a causal ring about it, which is in some contrast with the predominantly teleological tone of the rest of his writings; for instance, only a few pages earlier he has been speaking of the hair as having been arranged by God as “a shade in summer and a shelter in winter.” It is also true that Plato may have said more about the embryo than appears in the dialogues. Plutarch mentions various speculations about sterility, and adds, “Plato directly pronounoeth that the foetus is a living creature, for that it moveth and is fed within the bellie of the mothcr.”I

But all this was only the slightest prelude to the work of Plato's pupil, Aristotle. Aristotle‘s main embryological book was that entitled .-2:92 tqiwv yn'éaem;, On the Generation of Am'mal.r, but embryological data appear in neg! {'q5wv, T In Hirtwy of Animalt, :1eglCz_z‘:a.vv yoglm, On the Part: of Animalr, izegl tivanvafig, On Respiration, and 3591 lqfiwv xmia:w;. On the Illotion of Animalr. All these were written in the last three-quarters of the fourth century n.c.

With Aristotle, general or comparative biology came into its own. That almost inexhaustible profusion of living shapes which had not attracted the attention of the earlier Iom’an and Italo-Sicilian philosophers, Which had been passed over silently by Socrates and Plato, intent as ever upon ethical problems, but which had been for centuries the inspiration of the vase-painters and other craftsmen (twyguiglox), was now for the first time exhaustively studied and reduced to some sort of order. The Hippocratic school with their "Cmn classification of animals," which Burckhardt has discussed, had indeed made a beginning, but no more. It nae Aristotle who was the first curator of the animal world, and this comparative outlook colours his embryology, giving it, on the whole, a morphological rather than a physiological character.

The question of Aristotle's practical achievements in embryology is interesting, and has been discussed by Oglc.I There is no doubt that he diligently followed the advice of the author of the Hippocratic treatise on generation and opened {owl's eggs at different stages during their development, but he learnt much more than the unknown Hippocratic emhryologist did from them It is also clear that he dissected and examined all kinds of animal embryos, mammalian and cold-bl00d€d~ The uncertain point is whether he also dissected t.hc human embryo. lie refers in one place to an “aborted embryo,” and as he was able to obtain

I On Plato and preiorrnationiam, m Prueehter. I And Monulcnti.

easily all kinds of animal embryos without waiting for a use of abortion, it is likely that this was a human embryo. Ogle brings forward six or seven passages which all contain statements about human anatomy and physiology only to be uplained on the assumption that he got his information from the foetus. So it is probable that his knowledge of biology vms extended to man in this way, as would hardly have been the case if he had lived in later times, when the theologians of the Christian Church had come to severer conclusions about the sanctity of foetal as well as adult life.

The 11:91 Coin» yevéuemg, the first grmt compendium ofemhryology ever written, is not a very well-arranged work. There are a multitude of repetitions, and the order is haphanrd, so that long digrssions from the main argument are common. The work is divided into five books, of which the second is much the most important in the history of embryology, though the first has also great interest, and the third, fourth and fifth contain much embryological matter mixed up among points of generation and sexual physiology.

Book I with an introduction in which the relative significance of efiicient and final causes is considered, and chapters r to 7 deal with the nature of rnaleness and femalenm, the nature and origin of semen, the manner of copulation in different animals and the forms of penis and tests found in them. Chapter 8 continues this, and describes the diflhrult forms of uterus in different animals, speaks of viviparity and oviparity, mentions the viviparous fishes (the selachians) and draws a distinction between perfect and imperfect eggs. Chapter 9 discusses the Cetaoea; ro,eggsin general; and H returns to the diflerences between uteri. In chapter xz the question is raised why all uteri are internal, and why all testes are not, and in chapter r3 the relations buween the urinary and the genital systems are discussed. Copulation now receives attention agiin, in 14 with regard to Crustaea, in r 5 with regard to Cephalopuda, and in 16 with regard to Insecta. After this point the argument lifts itself on to a more theoretical plane, and opens the question of pangenesis, into which it mters at length during the course of chapters 17 and r8, refuting eventually the widely ‘held View that the semen takes its origin from all the parts of the body so as to be able to reproduce in the oflspring the characteristics of the parent.‘ The nature of semen receives a long discussion; it is decided at last that it is a true seuetion, and not a homogmeous natural part (a tissue), nor a heterogeneous natural part (an organ), nor an unnatural part such as a growth. nor mere nutriment, not yet a waste product. It is here that the theory

I Spedxl mum of Aristotle‘: qainions on heredity will be round in Iohanrrsen; '

Balsa (r923); H. Mew: (r9r9); and Snebitz.

is put forward that the semen supplies the “farm" to the embryo and whatever the female produces supplies the matter fit for shaping. The obvious question has nwrt to be answered, What is it that the female supplies? Aristotle concludes in chapters 19 and no that the female does not produce any semen, as earlier philosophers had held, but that the menstrual blood is the material from which the seminal fluid, in giving to it a form, will cause the complete embryo to be produced. This was not a new idea, but had already been suggested by the author of the Hippocratic neg! yorfig. What was quite new here was the idea that the semen supplied or determined nothing but the form. Chapters 21 and 22 are rather confused; they contain more arguments against pangenesis, and considerations upon the contrast between the active nature of the male and the passive nature of the female. Chapter 23, which closes the first book, compares animals to divided plants, for plants in Aristotle’: View fertilise themselves.

Book it opens with a magnificent chapter on the cmbryologieal classification of animals, showing Aristotle, the systematist, at his beathis classification is reproduced in Chart 1. But the chapter also includes a brilliant discussion of epigenesis or preformation, fresh development or simple unfolding of pre-existent structures, an antithesis which Aristotle was the first to perceive, and the subsequent history of which is almost synonymous with the history of embryology. The question in its acutest form was not settled until the eighteenth century, but since then it has become clear that there were elements of truth in the opinion which was the less true of the two. Chapter 2 is not so important. though it has some interesting chemical analt-gin; it compam semen to a foam, and suggests that it was this foam, like that of the sea. Whifll gave birth to the goddess Aphrodite.I But chapter 3 returns to the high level of speculation and thought found in the opening pan of the book, for it deals with the degree of aliveness which the embryo has during its passage through its developmental stages. Aristotle doesnot here anticipate the form of the recapitulation theory, but he certainly augguts the essence of it in perfectly clear terms. This chapter also an interest for the history of theological embryology. 50! its dd¢“P"°l‘ of the entry of the various souls into the embryo was afterwards made the basis for the legal rulings concerning abortion‘ This chapter also discusses embryogenyas a whole, as does the succeeding one. Chapter '5 is at digression into the problem of why fertilisation by the male is necessary, but it has also some curious speculations as to what extent the hen's egg is alive if it is infertile. The main thread 13 resumed in

. To mg amt, xll natural fotuns possessed a geaaen-itite virtul. In“ I 5'"! Arhfim wu wonltipped .2 Phtrie in '1'hnoe.






"Testaceaus animals have no sexes, and one does not generate in mother, they dn not bear fruit from themselves like plants, but they are formed and generated from a liquid and earthy concretion"


(nppmximntely corresponding

(approximately corresponding to Vcnebnllcs)

Vivlparous Inferlile


Oviparous "an egg is that from a part of which

the young comes into being"

Internally Externally ViVipXIll'0I.I5 Vlviplarous i.c. not springing i.c. springing from any egg from an egg

I Hiped: Q|.uIdr|\Jptdl I-‘nodes: Man Ilonu DaI[:Iu'nx Cam: and all Camera

Camlazhxauxfirhu Viper:

ta invertebrates)



I 1 e. eggs which have

hnrd ahcll: and do not increase in size after beirig laid

liipeda Qundrupeds Bird: Lunnlx Tartoire: Snake:


Le. eggs witich have no hard shells and which increase in size after llrcing laid Amfihibia Pirtu Cruxtazea Ceplmlapodn Sam: insert:

Those which produce a scale: or grub. “The whole of a scale: is developed inm the whole of a living animal." “All the products that are at‘ the nature of a reolex, after progressing and acquiring their full size, become a sort of egg“ (i e. 2 pupa). The scalar is thus an egg laid before it is mature

chapters 6 and 7. two very fine ones, in which embryogcny and foetal nutrition are thoroughly dealt with, but dropped again in the last sec. tion, chapter 8, which is devoted to an explanation of sterility. This ends the second book.

The third book is chiefly concerned with the application of the general embryalogical principles, described in the previous book, to the comparative field, and the fourth book contains a collection of minor items which Aristotle has not been able to speak of before.

But if the work as a whole tails off in a rather unsatisfactory manner, its merits are such that this hardly matters. The extraordinary thing is that building on nothing but the scraps of speculation that had been made by the Ionian philosophers, and the exiguous data of the Hippocratic school, Aristotle should have produced, apparently without effort, a text-hook of embryology of essentially the same type as Graham Ken:’s or Balfour's. It is even very possible that Aristotle was unacquainted with any of the Coan school; for, though he often mentions Democritus, Anaxagor-as, Empedocles and even Polybus, yet he never once quotes Hippocrates, and this is especially odd, as Aristotle is known to have collected a large library. Perhaps Hippocrates was only known to Aristotle as an eminent medial man; it’ this is so, Aristotle's achievements are still more wonderful.

The depth of Aristotle's insight into the genemtion of animals has not been surpassed by any subsequent ernbryologist, and, considering the width of his other interests, cannot have been equalled. At the same time, his achievements must not be over-estimated. Charles Darwin's praise of him in his letter to Ogle (which is almost too well known to quote) is not without all reservations true.‘ There is something to be said for Lewes as well as Platt. A.ristotle’s conclusions were sometimes not warranted by the facts at his disposal, and some of his observations were quite incorrect. Moreover, he stood at the very entrance into an entirely unworloed field of knowledge; he had only to examine, as it were, every animal that he could find, and set down the results of his work, for nobody had ever done it before. It was like the great days of nineteenth-century physiology, when, as the saying was, “a chance cut with a scalpel might reveal something of the first importance."

8. The Doctrine of the Menstrual Blood

As has already been said, Aristotle regarded the menstrual blood as the material out of which the embryo was made.

I “Linnaeus ma Cuvier have been my me gods. though in my d-Ema! Wm» ‘M they were mere schoolboy: to old Aristotle." C. D. to W. 0. 22/2/1882, from Li]: and Lertnr, ed. F. Darwin, 1888, vol. 3, p. 152.

That. then, the female does not contribute semen to generation [says Aristotle], but does contribute something, and that this is the matter of the catamenia, or that which is analogous to it in bloodless animals, is clear from what has been said, and also from a general and abstract survey of the question. For there must needs be that which generates and that fmm which it generates, even if these he one, still they must be distinct in fonn and their enenoe must be different; and in those animals that have these powers separateintwosexesthehodyandnatnreoftheactiveand passir-esexalsodilfer. It’, then, the male stands for’the effective and active, and the female, considered as female, for the passive, it follows that what the female would contribute to the semen of the male would not be semen but material for the semen to work upon. This is just what we find to be the case, for the catamenia have in their nature an allinity to the primitive matter.‘

Thus the male dynamic element (‘rd Eggs: zwmmrér) gives a shape to the plastic female element (16 01710 :ra0:rm:u5v). Aristotle was right to the extent that the menstrual flow is associated with ovulation, but as he knew nothing of the mammalian ovum, and indeed, as is shown in his crnbryological classiiimtion. expressly denied that there was such a thing, his main menstnraticn theory is wrong. Yet it was not an illegitimate deduction from the facts before him.’

9. Denials of Maternity and Paternity

These views of Aristotle‘: about the contribution of the female to the embryo are in striking contrast with certain conceptions of a century before which were probably generally held in Greece. There is a most interesting pzssage relating to them in the Eumenides of Aeschylus, when, during the trial scene, Apollo, defending Crests from the charge of matricide, brings forward a physiological argument. "The mother of what is called her child," Apollo is made to say, "is no parent of it, but nurse only of the young life that is sown in her (rgoéti; dd xziyara; rcoomfgoo). The parent is the male, and she but a stranger, a friend, who, if fate spars his plant, preserves it till it puts fort "

There is evidence that this doctrine was of Egyptian origin, for Diodnrus Siculus says, "The Egyptians hold the fatheralone to be the author of generation, and the mother only to provide a nidus and nourishment for the foet:us."' Whether this was so or not, the influence of snch a doctrine must have been tremendous. We know that the concqmon offhc female sex as playing the part affarrmland, i.e. of woman ‘5 5 field “' Wludl BT31“ Was sown, was widespread in antiquity; Hartland' and S. A. Cook‘ have collected examples of 1' t from Vedic, Egyptian and Talmudic sources. A late echo of it is to be found in Lucretius, who refers to "Venus sowing the field of woman"-

‘ 719‘ 2:. "l'hefurther(ondlvng)hi:toryofthistlteorywillbefotrmiprinei-pallyonpp.73. l45—6IIIt‘la.37—8, below. X-‘orAris*tutie,Is l'or|llo1.h¢rGreelurthm!. tltetne-nstrual blood urn normally an auction oi impure material. Cf. the impurity of the wunun producing it in folklore, both modem Ind indent Greek (Lit-ht, vol. 2, p.77; Crawfurd). Btochelrlial investigatiom have teltufively traced the inhibitory and other hiologiml efiedsufmeltstruzlhloodIndthelweatoflnaastrlutingvrunentolhepreseneeof considerable amount: of the base choline. ' Ipeb cdn. p. :75.

atqne in cost Venus ut muliehria conserat arva.’

Nor would resemblances between mothers and children sudiee to kill this belief, for plants may differ slightly according to the soil in which they are planted. Such an idea would have been a natural concomitant of the practice-——also widespread in antiquity—of putting mptured males to dath, Ind retaining the females as concubines. The conquerors would thus have had no fear of corrupting the race with alien blood. The whole matter affords an excellent illustration of the way in which an appnmntly academic theory may have the most intimate connections with social and political behaviour, and Aristotle, far from being remote from practical afiairs as he examined his viviparous fishes and made marginal notes on his copy of Eznpedoclcs, is seen to be labouring at their very root.

Then: is a good deal more to be said about this Graeco-Egyptian doctrine, which we might term "the denial of physiological maternity.” For its precise opposite is met with in anthropology—"the denial of physiological paternity." Just as the Egyptians claimed that the father alone produced the child, so the Melanesians claim that the child is produxd solely by the mother.

Malinon-sky, in his brilliant account of the sexual life of the Tro~ hriand Islanders,‘ describes their belief that children originate only in Tuma, the spirit-world,‘ and that sexual intercourse has nothing whatever to do with pregnancy and childbirth. Of the fertilising power of semen, they have, according to him, no idea. Tuma is :1 kind of world of the unborn, reminiscent of Cooke's eighteenth-century theory (see p. 208) and of Origen‘s pre-existence (see p. 95 n). Menstrual blood 18 the substratum of the embryo, and souls come to inhabit it as it accumulates in individual bodies.

i‘;'u':".i€r7_'.o°.,”ia'motht: in S<v'pgo°cllc:x,' }’i;.§.,§Z;.., 1. 569:

Innate. Inn than my the betrothed of thine own son? Cum. Nay, there are other fields for him to plough.

(dgduugmt 7&9 gdrégm 21:12! you»).

2%‘: '.icl"¢ii72xi.ii£.i.iir' Arum: in the origin of ehildren rm. mrappa scones, dcscribed Ivy Spencer 5: Gllltn, vol. 1, p. 363; and now by Ashki Menus‘-

(1937; Vaughan has nu-um explored the Greek parallels.

The Trobrianders‘ argument, when pressed, was twofold: (1) that women were often sterile, even when married and having frequent sexual intercourse, and (2) that unmarried girls, though permitted by custom to have sexual intercourse, invariably remained sterile until officially married. Nothing could be said against the first of these observations, but the second presented a sufficiently intriguing problem, not for the anthropologist only, but also for the biologist. Malinowsky was able to convince himself that contraceptives were not in common use, and the subject remained something of a mystery until Hartman discovered a’ high relative sterility of the adolescent organism in experimental colonies of apes. Puberty and maturity, as he points out, are neither synchronous nor synonymous. In Hartman's colony, the young females were mated at the first menses (wt. 3350 gm.) but not a single female conceived before attaining the weight of 4400 gm. Mirslraia 8: Crew, again, observed in the mouse that pregnancy followed first mating in only 7.4, per cent. of the cases, while the same mice were 9o per cent. fertile in later matings. In India (see p. 26), where cohabitation began from about 12 years onwards, returns from maternity hospitals placed the average first parturition at about 19 years (r8.3—rg.4, Clark). The same picture is given by Mondiere for Cochin-China. Malinowsl<y's phenomena, says Hartman, are probably explained by the fact that the first menstruation (puberty) marks merely an early manifestation of a train of events (adolescence) which only after three or four years leads to ovulation and conception, the proof of maturity. This explanation is made more plausible by the fact that although childbirth before marriage was stated to be exceedingly rare among the Trobrianders, occasional cases occurred.‘

Much interest attaches to the further problem, namely whether these two opposed theories of primitive man—the denial of physiological paternity and maternity respectively—could have had any connection \vith the patriarchal and matriarehal frameworks of human societies.‘

Finally, the rsemblance of the Graeco-Egyptian view to the consequences of extreme anirnalculism (see pp. 205-12 of the present work) should be noticed. On the whole, the eighteenth century refrained from drawing the logical consequences of animalculism as regards heredity, and sometimes saved the situation by falling back on the force of the mother's imagination (see p. 215), etc., but a remark of Good,‘ who

‘ Cl. the review on adolescent rterili b Ashl Manta r .

After ptvpoling this connection, X feyarnyt that ifie ormiixiifégia had been made the basis of similar argument: by J. J. Bachofen in his Itlum-null! u. Urrtligfzm, P175, 57 F. Engels in his L'on'g|'n: dc lafamillt, dz Ia propriltl Prick, 2: dz l':'!a_l. p. xvii. Inc] I: G. P. ’I‘hornson in Aerrhylru and Atlmu, p. :87. Cf. Bach-afen 3 Uhrzllgian un mlike Syn-tbale. pp. n4 ff.

' Lucretius translation and notes, voL 2. pp. :96 0'.

Wfrgtf 1!} I805. unearthed by core; is very illuminating. Speaking 0 e wide acceptance of the ammalculist theory during the preceding fifty Y¢‘”‘-‘he SW51 "EVCry naturalist, and indeed every man who pretended to the smallest portion of medical science, was convinced that his children were no more related, in point of actual generation, to his °“'n Wife: than they were to his neighbour’s."|

)0. Formation, Recapitulation and Fermentation

’l‘he embryo, then, took its origin from the menstrual blood, on wluch, and_rn which, the seminal essence operated to produce it. But the perplexing question of the order of formation of the pans remained unskilled, though it had already been opened by earlier thinkers. What they had not done was to put the question, as it were, into the form of a motion; they had not grasped the existence of two main altemativ , one of which would have to be chosen before any further progress could be made. This is just what Aristotle did:

There is considerable difhculty in understanding how the plant is formed out of the seed or any anirrral out of the semen. Etcrything that comes into being or is made must (x) be made out of something, (2) he made by the agency of something, and (3) must become something. Now that out of which it is made is the material; this some animals have in is first form within themselves, taking it from the {cattle parent, as all those which are not born alive but pmduccd as a rrolzx or egg; others receive it for a long time from the mother by sucking, as the young of all those which are not only externally but also internally viviparous. Such is the material out of which things come into being, but we are now enquiring not out of what the pars of an animal are made, but by what agency. Either it is something external which malts them or else itis something existing in the seminal fluid and the semen; and this must either be soul or :1 part of a soul, or something containing soul.‘

Aristotle concludes that there is no external shaping influence, but only something or other contained in the embryo itself. To this extent he was wrong, for the influence of the proper physico-chemical environment on

‘Early TI:zon'u, p. rzz. _ _ ‘ With this may be compared the curious pusages In L. §teme'I Tmtnzm Shard)’ which drsarss the proposition that the mother 1: not of Inn to her child (Book IV, chapter :9), and the lung consideration which Boswell glye (vol. 1. p. 428 H) to the question of whether his family estate should be tnmledfor h:us_ general or male heir! only (1776). "I had," he tells us, “a zealous psrtialrry for hens male, however

remote, which X maintained by arguments which Ippcared to rne to have conlid:_nbl_e ‘ ‘shed narur-rhsu. that our Ipcmi 11

weight. Ar. Eat, the opinion of some disttngur _ mnmrmd through mules only, the female being .11 along no more than . nrdus, or nune, as Mother Earth is to plants of every not-t',whi<.h pntwn seems to be wnfirmvd by out text cfscriptu.rr.——‘}-le was yet in the loins of his Father when Mzlchu-tdck met him’ (Heb. Vil. ro)." etc., etc. In spite ofthe (Earl: of Lord trams Ind Dr Johnson. Boswell retained the psrtrahty the growing embryo is as important as its physico—chemical internal constitution (later he modified his views on this). But now he goes on to deal with the main question, and says,‘

How thm does it (the shaping influence) make the other parts? All the parts, as heart, lung, liver, eye and all the rest, come into being either together or in sucoesion, as is said in the verse ascribed to Orpheus, for there he says thatanauimaloornesintobeinginthesamewayastheknittingofanet.That the former is not the fact is plain even to the senses, for some of the parts are clearly visible as already existing in the embryo while others are not. That it is not because of their being too small that they are not visible is clear, for the lung is of gruttersizethanthchmrgandyet appears later than the hmrtin the original development.

This passage demonstrates that Aristotle had opened hen’s eggs at different stages, and was well acquainted with the appearanew presented there as early as the third day. He goes on to set forth a further alternative. Agreeing that a continuously new formation of parts takes place, and not merely an unfolding of parts already present in the semen or the menstrual blood, is this brought about by a chain of creations or by one original creation I In other words, does the heart come into being first, and then proceed to form the liver, and then the liver go on to form the lungs, or do they simply appear one after the other without such a creative inter—relationship P Aristotle argues against the former view on the ground that if one organ formed another, the second one would have to resemble the first in some way, which is not the case. His words on this subject mnnot be condensed.’

But neither an the(fom-native) agentbe aternalandyet it must needs be one or other of the two. We must try then to solve this difficulty, for perhaps some one of the statements made (already) cannot be made without qualification, e.g. the statement that the parts cannot be made by what is external to the semen. For if in a certain sense they mnnot, yet in another sense they an. [Thus Aristotle does some justice to the environment] It is possible, then, that}! should move B and Bshould move C, that, in fact, the caseshould be the same as with the automatic machins shown as curiosities. For the parts of such machines while at rest have a sort of potentiality of motion in them, and when any external force puts the first of them into motion, immediately the nctt is moved in actuality. As, then, in these automatic tnachines the t-Jtternalforcemovesthepartsinacert:Iinsense(notbytuuchinganypartst the moment but by having touched one previously), in like manner also that from which the semen comes, or in other words that which made the semen, set: up the movement in the embryo and malt: the parts of it by having touched firs: something though not continuing to touch it. In a way it is the motion that does this. as the act of building builds a house Plztlnl then. while there is something which makes the parts, this does not iatist as’; definite object, nor does it ads: in the semen at the first as a complete pan,

This idea of the setting in motion of a wound-up cloclt is substantially modern and underlies the physico-chemical analysis of the developing embryo. It is really striking to find Aristotle using the machine analogy in order to explain himself, for he, of all biologists, emphasised the final txiuse in natural operations. However, he soon returns to a more vitalistic attitude in the succeeding section.‘

But how is each part formed? We must answer this by starting in the first instance from the principle that in all products of Nature or art, a thing is made by something actually existing out of that which is potentially the same as the finished product. Now the semen is ofsuch a nature and has in it such a principle of motion, that when the motion isceasingeachof thepartscomes into being and that as a part having life or soul. . . . And just as we should not say that an axe or other instrument or organ was made by the fire alone, so neither shall we say that foot or hand were made by fire alone. . . . ‘While, then, we may allow that hardness and softness, stickiness and brittleness, and whatever other qualities are found in the parts that ha": life and soul, may be mused by mere heat and cold, yet when we come to the principle (léyo,-) in virtue of which flesh is flesh and bone is bone, that is no longer so; what malt: them is the movement set up by the male parent, who is in actuality what that out of which the ofispring is made is in potentiality. That is what we find in the products of art; heat and cold may make the iron soft or hard, but what makes a sword is the movement of the tools employed, this movement containing the prineiple of the art. For the art is the starting-point and form of the product; only it exists in something else (Le. potentially in the mindof the artist) whereas the movement of nature exists in the product itself, issuing from another nature (i.e. the parent) which has the form in actuality.

Thus Aristotle, evidently influenced by his doctrine of "form" and “matter,” decided against preformation and pictured at one and the same time the unforrned cataznenia as containing a kind of clockmirk mechanism which, once set in motion, would inevitably pruducethe finished embryo, and also as an inchoate substance on which the seminal essence should act like a swordmaker producing a sword according to the motions of a natural art.‘ These two ideas are not completely reconciled in Aristotle, and a consideration of artificial fertilisation would have provided a test case, had he been able to know of the experiments of Delage and Loch. For on his second theory, butyric acid would transmute a sea-urchin’s egg into butyric acid and not into a sea-urchin; while, on his first theory, the egg would make the sea-urchin irrespective of what influence it was that swung the starting-handle.

’ Biiiss ([936, p. 6o) interprets Aristotle is leaning more to the fan-net oI_theseft::t; iaeiii than I did uiiziii am wrote the thaw: passagfi. If in. she w:r;“=,=Ph°§ ° ” moving B and 3 moving C" and lhe_l|-inlagy pf the ilutfltnfluc ms nee i aw‘; turlosltr 2 . remarkable vindication of Aristotle's insight; -ms: modem em ryn1ogy_ wit 1. theory of fin:-, seeornd-iid third-grade organisers, bu found oi-my rim of this kind. The ne_unl qimn ii iiiduged by the pnimiy dorsal iip organiser. ind the imi of Xilfl eye In turn by the who _cutgrowth or die new-I swim (M Needham, 1936; iqso). Many other cases at‘ this lucccssmn ol‘ influei-ion Ire aawn.

Aristotle has a good deal to say about the theory of recapitulation, as it was afterwards to be called. He thought there was no doubt that a vegetative or nutritive soul‘ existed in the unfertilised material of the embryo, for nobody would put down the unfertilised embryo as soulless or in every sense bereft of life (since both the semen and the embryo of an animal have every bit as much life as a plant) and it is productive up to a certain point. . . . As it develops it also acquires the sensitive soul‘ in virtue of which an anim.-il is an animal. . . . For first of all such embryos seem to live the life of a plant, and it is clear that we must be guided by this in speaking of the sensitive and the rational soul.‘ All three kinds of soul, not only the nutritive, must he possessed potentially before they are possessed actually.‘

These passages show very clearly the line of thought contained in the recapitulation theory, as do the following.‘ "An animal does not become at the same time an animal and a man or :1 horse or any other particular animal,” i.e. the more general appears first and the more particular later. “The end is developed last, and the peculiar character of the species is the end of the generation in each individual,” i.e. the embryo attains the point of being definitely not a plant before it attains that of being definitely not a mollusc but a horse or a man. Aristotle concludes that the different sorts of souls enter the embryo at different stages of development, just as the shape of the embryo gradually approximates to whatever adult shape it is destined to possess.‘ He did not think, how-

and it has been suggested as the explanation of the (sets for which the rec-apirulation theory was fashioned (Needhnm, 1930). .

Another argument used against prefonnation by Aristotle was that if the embryo win preformed either in the male or female contributions to generation, I double o_fl_’spring would alurny: result. Balsa (x936) points out the shzrpsightcdncss of !h1S_ criticiszri, which really did not receive an answer till the discovery of the reduction division of the chromosomes two thousand years later.

‘ “W vvzr) 0L’”‘“’"i’ The iwzrl aYU9'Fwi' Th‘ V"-'Z'l "“**°’F°='l-

‘ 736‘ 33:cf. Schmidt. ' 736‘ 2. _ _

' On Aristotle’: doctrine of souls cf. Sir Thomas Browne: "\Vho admires not Regiorrlontanus his Fly beyond his Eagle, and wonders not more It the operation of mo souls in those minute bodies, than but one in the trunk of a cedar?’ It has recently been shown that closely similar doctrines of I ladder or succtssion of soul: or vital force: in ontogeny md plrylogenyvtere current in Chinese thought through the ages (nee Lu Sc Needlinm, and more fully in Sritnze and Cinlixutfon in Chino, vol. 1). The dating of the thinkers concerned makes my transmission of Greek ideas very improbable. _

The recapitulrrion theory has an entenairiing echo in sixteenth-century theological

W“! ‘hm “WY were in-breathed from any source external to the embryo but rather that they were internally generated each in due time x ’ Aristotle continues to discuss the central problems of embryology . . .

.:lt:ll:<::\I' tn a way which presents features of directly physicg.¢},¢mica1 When the material secreted by the female in the utenis has been fixed by the semen of the male (this act: in the same my as rennet acts upon milk,’ for rennet 1! a.lur_id of containing vita] heat, which brings into one mass and 5*” "'3 Slmlhl’ mflltfllli and the relation of the semen to the citamenia is the same, ‘milk and the mtarnenia being of the same nature), when, I say, the more solid part eomes together, the liquid is separated afl' from it, and as the earthy pans solidify membranes form all round it; this is both a necessary result and for a final cause, the former because the surface of the mass must so1idify_ on heating as well as on cooling, the latter beaiuse the foetus must not be in a liquid but sepanted from it.

Later on, he also says,’

The reason is similar to that of the growth of yeast, {or yeast also grows great from a stnall beginning as the more solid part liquefis and the liquid is aented. This is eifected in animals by the nature of the vital hurt, in ymsts by the heat of the juice contained in them.

polemic. for the Epirlolae Obtanarinrl Vinmnn, written on the Protesnnz side in German In naicun, tum aim, Catholic icnzpulonry, contains (p. my the falluvrulg:

mm nvi. Ham-21. Szhaujnuml lo Mag omna. swim.

"I write to ask your rcvereyiee what opinion you hold concerning one who on I Friday . . . should car In eg with 1 chicken u. n. For you must know um we were lately iitting in en inn in the Campo dei Fion, hai-mg our iupper, and were eating eggs, when on opening one I saw out there was . young chicken within. This 1 showed to cvmrnde, whereupon quoth he to me, ‘P4: I! up lpeedily, er: the merrier see it, {or if he mull it. you will have tn pry . . . for n 1'oivL It is is rule of Lhehouse thnr once the landlord has put anything on the table, you must pay for it, he won't like it back.‘ . . . In I tr-ice I gulped down the egg, chicken and all. and then I remembered that it was I Friday. So I aid to my companion, ‘You have made me corrmnit

mumi sin in eating flesh on the sixth day of the week.’ But he even-ed it vns no mortal sin, nor am I mu.-ii me, seeing that Inch . chick in Iccaunted an egg mmiv. until it is born. He told me, too, that it isjiist the same i.n the use atcheese. In which there tre sometimes mites. ii: there are nuggets in cherries. pen, or new buns; yet all time nuy be eaten on Fridays and even on Aposioli: Vigils. But raverneis Ire xu rascals that they all them flesh, to get the more money. This 1 departed. end though: the mutter over, end, by the lard, Mister Gr-tiui, I In: in 1 mighty quandary and know not what to do. . Ir um-ieth to II}: that these young {owls in eggs in ljesh. because their Iubsturi for-med im_d fashimied_mto the limbs Ind body of an Il’LIfl'lI-lr ind possesseth a vital principle. It is difierent in the cue of gheese-nuts and ouchlike, because grub: are ncmunted ash, as 1 lamt from . physician who is {killed -1” in natural philosophy. Most urriestly d_o entrmr you to resolve the question} have gropatmdtd, for if you hold that the sin is martnl, then I would {an get nhnft her:

dare I return to Germany."

I See the careful study of l\Iui1_u.x._ , ‘ 7:9‘ :2. on Ar-istnt 2'3 chemicll Ida! see vim L-ppmxnm

' These remarkable passages contain the first reference to enzyme action ever made in a discussion in embryology. The solidifimtion of the outer cnrst is of course Hippocratic, as we have already seen. The part about the arnnios is tmfortunate; for the facts are exactly contrary.

The heart is first ditferentiated [says Aristotle‘), as is clear not only to the senses (for it is so) but on theoretiul grounds. For whenever the young animal has been separated from both parents it must be able to manage itself, like a son who has set up house away from his fathu.

This is good observation. "The heart is the principle and origin of the embryo,” says Aristotle.’ This conception of carprimrnu vivens, ullirnum mmieus (a phrase never used by Aristotle himself) has henceforward a long and tortuous history, which has been described by Ebstein and others.

Aristotle goes on to clscribe the membranes of the mammalian foetus with its umbilical cord 9 “The vessels join on to the uterus like the roots of plants and through them the embryo receives its nourishment. This is why the unbryo remains in the uterus"; not 3 Democritus thought, so that it might be moulded into the maternal shape. The embryo "straightway sends oi? the cord like a root to the uterus.” He carefully notes, as if the oonoeption of axial gradients was existing deep down in his mind, that the cephalic parts of the embryo are formed first.‘

The greater become visible before the leg even if some of them do not come into being before them. First the parts above the hypezama [a term more or less eorresponding to "diaphragm"] are differentiated and are superior iuxize; thepart below is both smaller and less differentiated. This happens in all animals in which exists the distinction of upper and lower, except in the insects.

Aristotle gives his explanation of this a teleological argument:'

This is why the parts about the head and especially the eyes appear largest in the embryo at an early stage, while the parts below the umbilieus, as the legs, are small; for the lower parts are for the salte of the upper and are 'ue'zrbn:r]7'4tts tfifire enh, nor a'o‘re'm'iorrn3t.

Embryonic growth is thus described by Aristotle?

The homogeneous parts (tissues) are formed by but and cold, for some are put together and solidified by the one and some by the other. . . . The nutriment oozes through the blood-vaels and the passage in each of the parts, like water in unhsked pottery, and thus is formed the fish or its aualogua, bdng solidified by cold, which is why it is dissolved by fire. But all the particles given off which are too earthy, having but little moisture and hat,

‘-ms‘ 3. -7.5:-2:. -74¢-3;. ‘7Ql‘ :6. '74:‘ 14“Mrs-

cool as the moisture evaporates along with the heat, so they become hard and earthy in Chamcmir 35 "339: h°m3. hoofs and beaks, and therefore they are softened by fire but none of them is melted by it, nhile some ofthem as e . shells, are soluble in liquids. The sinews and bones are fanned by thelinm-$1 hut as the moisture dries, and hence the bones are insoluble by fire like pottery, for like it they have been as it were baked in an oven by the heat in the process of development. . . . The skin, again, is formed by the drying of ‘he flfih. “lit the Scum upon boiled substances; it is so formed not only because itis upon the outside, but also because what is glutinous, being unable to evaporate, remains on the surface.

Hero is a splendid collection of mechanical processes, but Aristotle is careful to add? “As we said, all these things must be understood to be formed in one sense of Necessity. but in another sense not of Necessity but for a Final Cause.”

Concurrent growth and differentiation, the former being temporally sequent to the latter, he thus describes :1

Theupper half of the body,then, is first marked out in the order of development; as time goes on the lower also reaches its full size in the nznguinea. All the parts are first marked out in their outlines and acquire later on their colour and sofrneg or hardnesa, exactly :5 if Nature were a painter producing a work of art, for painters too first sketch in the animal with Jinn and only

after that put in the colours.

Aristotle had some difficulty about the eyes; he noted that they were very disproportionately large in early bird embryos, but he seems to have thought that they shrank absolutely as well as relatively during further development. It takes him a great deal of ingenuity to invent a teleological explanation for this quite imaginary fact.

The food which the embryo derives from the mother, according to Aristotle, is of two distinct kinds, nutritious, formative or creative, rd 0ge:rn1:dz', and that which is concerned with simple increase of size, 16 ct‘; ,uéyI:0o; .-torof-at 27):! eiztldocrm This distinction is dificult to undersrmd, and, though. it would be attractive to interpret the former as vitamins and the latter as fats, proteins and carbohydrates, that would probably be putting too much of a strain on our belief in Arrstotlds insight. He hm much to say of the placenta, and ascribes to rt rts_correct function. He combats the idea that foetal nutrition rs maintained by uterine pups, alleging against it the fact that all embryos are enclosed in membranes. He discussa birds’ eggs in great detail. rffcfimg '0 infertile or "wind—eggs" and to the action of heat 4111198 m°“l7‘f"°“He considered that the embryo was formed from the white exclusively, and only got its nourishment from the yolk. which was a backward step in view of what had already been said by the Hippocratic embryologist. He knew of the whiteness of the yolk when first formed in the oviduct and of the yellow colour of the layers of yolk added to it in its passage down that tube, but he held that the yellow colour was "sanguineous," and therefore hot, while the white was cold. He held also that the bird embryo alwmys developed at the pointed end;‘ no doubt, as Platt has suggested, Aristotle belonged to Swift's class of “little—endians," and must have always opened them at that end, in which case he would find the embryo there, for the yolk always swims embryo uppermost. He knew also that the yolk liquefied during the first week of development, and that it grew larger, but he did not guess the right rasons for these phenomena. He knew the arrangements for embryonic development in the dolphins and ovoviviparous sharks.‘ He takes a strong line over spontaneous generation; "nothing," he says,’ "comes into being by putrefying, but by concocting.” And. so in many other passages where detailed observation isjoined with acute reasoning.

So far only the treatise on the generation of animals has been under consideration. But in the negl Ctfmw, also, there are many embryological data, and it is strange that those detailed observations upon the developing fowl tnnbryo, which demonstrate more than anything else Aristotle's wonderful powus of observation, are not contained in the Genenzlion of Aninml: at all, but in the Histmy of Animalr. He takes animals one by one in order, and in each (arse deals with their generative peculiaritis, such as their mode of hatching, their incubation period, their fertility, etc. For imtmm be correctly relates how the embryos of cartilaginous fishes possess a yolk-sac like bird embryos, but no allantois. In his aeetnmt of the fowl he is unusually precise.‘

Most of the sixth book is occupied with the accotmt of the generation of birds and fishes, and the seventh treats also very fully of that of man. But in both cases it is description that is given; the theoretical considerations are left to the book on generation, and for this rmson the latter work is the more interesting. The Hiuary 1] Animal: has a wonderful wmlth of tnatuial in it, but at the same time inehida rmny attravagant stories, such as those of the "kindly and gentle dolphin" and the equine Oedipus, so that the austuity of the book on generation charms us more.

‘ 794' m _ ‘ 'l'IIe_plaoentoid structure in Illurtelur Ian‘: WI: rediscovered by Johannes Muller In the nineteenth century; the full Irory is grvm by Haberlxng.

‘ 76:‘ 14. See on the quation of sponxanmus generation nnantique authors including Aristotle) \-on Lippmonn Ind Rodemer. Later Rabbinic texts martian ink is onginating from the slrme at the nu (e.g. Peiiqln Rabbauxi, ed. Friedmann, p. om).

reference to Dr H. Loewe.

Other treatises also mention ernb I . Tl: ‘ ' the Paris of Animals, has a passage inriifliifli the day chick embryo is described, and refers to observations on the lack of prgrnent and of distinct medullary canals in bones in foetal life. The small work entitled neg! dm.-n'm'i§: On Re;-piralian, also refers to the heart as the first organ to be formed, and so as the seat of the soul. But these minor sources contribute little to the progi-555 of thg scimcei and it rs upon the great work On the Generation ofAnx‘rnalr that Aristotle's well-deserved fame as an cmbryologist will always rest.I

The Aristotelian Balance-sheet

If I have devoted such ample space to an account of Aristotle’; contributions to embryology, it is, firstly, because they are actually greater in number than those of any other individual embryologist, and secondly, because they had so profound an influence upon the following twenty centuries. Embryology from the third century a.c. to the seven» teenth century )\.D. is meaningless unless it is studied in the light of Aristotle.

His outstanding contributions to embryology may be put in the following way:

1. He carried to their logical conclusion the principles of the observation of facts suggested by the unknown Hippocratic cmbryologist, and added to them a discipline of classification and correlation of facts which gave embryology a quite new coherence.

2. He introduced the comparative method into embryology, and by studying a multitude of living forms was able to lay the foundation for future science of the various ways in which embryonic growth can take place. Thus he lmew of oviparity, ovoviviparity, and viviparity, and one of his distinctions is substantially the same as that known to modern embryology between hoioblastic and mcroblastic yolks.

3. He distinguished between primary and secondary sexual characteristics.

4. He pushed back the origin of sex-determination to the very begimting of embryonic developmerrt.‘ '

5. He associated the phenomena of regeneration with the embryonic state.

6. He realised that the previous speculations on the formation of

On the Generation

I Our knowledge of the numerous later translation: of Aristotle‘! but sum,’ gm‘

nfAm'maI.r into Arabic, Latin and other languages. is :3-H xmperfzch work contain: a good deal of information on till: subject. cr. the special ltudy of am by Blend‘-

the embryo could be absorbed into the definite antithesis of preformation and epigenesis, and he decided that the latter alternative was the true one.

7. He put forward a conception of the unfertilised egg as a complicated machine, the wheels of which would move and perform their appointed function in due course when once the masterlevcr had been released.

8. He foreshadowed the theory of recapit-ulation in his speculations on the order in which the souls came to inhabit the embryo during its growth, and in his observation that universal characteristics precede particular characteristics in embryogeny.

9. He foreshadowed axial gradient theory by his observations on the greater and more rapid development of the cephalic end in the embryo.

10. He allotted the correct functions to the placenta and the umbilical cord.

11. He gave a description of embryonic development involving comparison with the action of rennet and yeast, foreshadowing thus our knowledge of organic catalysts in embryogeny.

But there was another side to the picture. Aristotle made three big mistakes, and here I do not refer to any matters of detail, in which it would not have been humanly possible to be more than very often right, but rather to general nations, such as the eleven correct ones just noted.

They were as follows:

1. He was incorrect in his view that the male supplies nothing tangible to the female in the process of fertilisation. To say that the semen gave the “form” to the inchoate “matter" of the menstrual blood was equivalent to saying that the seminal fluid carried nothing in it but simply an immaterial breath along with it. Aristotle could not, of course, envisage the existence of spennatozoa.

2. He was entirely wrong in his teaching about the xcalex. The caterpillar is not, as he supposed, an egg laid too soon, but has already passed through the embryonic state.’

‘ The study of metamorphosis in animals would be worth following all through the ages since the changes undergone by the pupa so closely resemble the differentiation of embryos. The time was to come, in the seventeenth century (pp. r39, :83 below), when [he study of insect morphogmcsia and the embryology of mammals were to react strongly togethef. But fin: it was necessary to dear away a mass of erroneous meduevsl beliefs about non-uistznt rnetamorphoses. For example. there was the ancient mph of the generation of geese from bramades, which natunlly played a not unimpommt part in moral theology. The best accounts of it are in van Lippmann

(pp. 36 if.) and in the monograph of Heron-Allen. The myth was subject, says HeronAllen, to a number of smaller or larger vnri-tions, bur, broadly speaking, it run that

3. He was misled by some observations a cast ' did not ascribe to the testis its true “mm”: and so

12. Aristotle’: Them-y of cgusgfion

Such mistakes as these however were not nearl '

. . , Y so 1 it t the sohcl ground gained by hm correi:t answers. They were lallliifaysazpeaii 3° °"P¢flm=fl‘31 "Sh even though the authority of his name precluded it until the Renaissance. But there was one aspect of his ernhryologieal work which was to exercise an unfortunate influence on the subsequent progress of the science, namely, his insistence on teleologimi exphng. tions. He was always seeking for final as well as eflicient museaa "The ancient Nature-philosophers did not see that the causes were numerous; they only saw the material and efficient causes and did not distinguish 9"“ ‘hfifv W131‘ ‘.119!’ grade no enquiry at all into the formal and final ca'iuses._ Democritus, he says, “neglecting the final muse, reduces to Necessity all the operations of Nature. Now they are necessary it is true. but yet they are also for n final cause, and for the sake of what is best in

each case." Aristotle’s theory of caussdon is best studied in the Pliysim (ig.i'

x6 fl'.). Santayana has applied it in an amusing passage to embryology.

Aristotle distinguished {our principles in the undenuinding of Nature. The ignorant thinlt that these are all, equally, forces producing change, and the cooperative sources of all natural things. Thus, ‘if i chicken is hatched, they say that the Elficient Cause is the warmth of the brooding hen, yet this heat would not have hatched a chicken out of a stone, so that a second condition, which they ull the Material Cause, must be invoked as well, namely, the nature of an egg: the essence of eggntss being precisely ii capacity to be hatched when warmed gently—heenuae, as they wisely nhsene, boiling would drive away all potentiality of hatching. Yet, as they further remark, gentle heat-in-general joined with the essence-of-eggncss would produce only

"the (rule: (or leaves) of certain trees, falling lnto the sea (or on land) become Barnacle: (or birds), or that the lliiri-iaelea ilianulvea grow upon a tree (or u on a log, or upon ‘hip’; fimben), uni when developed ro a eertain point, {all ofl'ar_i beeorne eeae (or ducks), in {ace the Blmsele-geese or Brent-zoos: Emmi be-mirIu)." The i-naele iwcliia at usuneaseevdcetnupede (crustacean , _ tetainson Itniaunt at the age of the legend the name Lffidl malt/no. Heroaea I conclusion is that the myth arose from the striking mun la_noe between the feathers of a bird and the plumose |ppn1_aagu on cirnpede. But its anti uiey u rather unexpected: he was able to trace Il may ya me Mymiaean age, thong _ it do: not oeuar in Graeeo-liornan literature. ordinary things about the barniiele-geiae legend is that it has

=|o(¢)e"e;i:;f;il‘¢eumii?lC‘l!un'u;e aoolagiul literature, also connecting birds and molluses.

hatching-as-such and not the hatching of a chicken, so that a third influence, which they call the Final Cause, or the End-in-view, must operate as well, and this guiding influence is the divine idea ofa perfect cock or 2 perfect hen presiding over the incubation and causing the mere cggness in the egg to assume the likeness of the animals from which it came. Nor, finally, do they find that these three influences are sufficient to produce here and now this particular chicken, but are compelled to add a fourth, a Formal Cause, namely, ‘a particular yolk, a particular shell, and a particular farmyard, on which and in which the other three causes may work, and laboriously hatch an individual chicken, probably lame and ridiculous despite so many sponsors.

Santayana puts this descriptiom into the mouth of Avicenna in his imaginary dialogue, and makes him go on to say,

Thus these learned babblers would put Nature together out of words, and would regard the four principles of interpretation as forces mutually supplementary combining to produce material things; as if perfection could he one of the sources of imperfection or as if the form which things happen to have could be one of the causes of their having it. Far differently do these {our principles clarify the world when discretion conceives them as four rays shed by the light of an observing spirit.

It is essential for an understanding of the following centuries to realise that these Aristotelian conceptions went without serious contradiction,’ and thus formed the framework for all the biological work that was done. Owing to its association with the idea of the plan of a divine being, the final cause tended in the Middle Ages to eclipse the others. In the seventeenth century this feeling is well shown in a emarkable passage which occurs in the Relxgio Media’ of Sir Thomas Browne:

There is but one first cause, and four second causes of all things; some are without Efficient, as God; others without Matter, as Angels; some without Form, as the first matter; but every Essence, created or untreated, hath its Final cause, and some positive End both of its Essence and Operation; this is the cause I grape after in the works of Nature; on this hangs the providence of God; to raise so beauteous :1 structure as the World and the Creatures thereof, was but his Art; but their sundry and divided operations, with their prcdstinated ends, are from the Treasure of his Wisdom. In the causes, nature, and affection: of the Eclipses of the Sun and Moon am, 5, mos, excellent speculation, but to profound farther, and to contemplate a reason ‘WY hi’ Pmfidence bath :0 disposed and ordered their motions in that 1 Circle as to conjoyn and obscure each other, is a sweeter piece of Reason :34 a divincr point of Philosophy; therefore sometimes, and in some things, there appears to me as much Dmmty Ln Galen his books De Um Pmlium, as in Suarez‘ Illtlaphyrickrz Had Aristotle been as eprious in the enquiry of this cause as he was of the other, he had not left behind him an imperfect piece of Philosophy but on absolute tract of Divinity.

‘ Actually Santayana used much philosophical licence in his account. The best explanation: of the Aristotelian causes I know of are in the brilliant introduction: to A. L. Peck‘: editions of the Generation ol Am'vr-alt (um) and the Pew '7/Ame!’ (I937). The more usual interpretation would he that the yolk and white of the egg are the Material Cause. the Iperrn of the cock the Efficient Cause. the generic and_spe_:-ifie nature of the animal (in this case I bird) the Formal Cause. and the end-in-View, the perfected adult cock or hen in the future. the Final Cause. Peck‘: introductions are worth V tareful amd ,

I Ct‘. Dantrz Puvgalario, harm; as and the comments of del Gaudio. See further, pp. 9; 1}‘. below.

This was written in Harvey's time, and in Harvey's thought the four causes were still supreme; his De Generation: Animalium is deeply concerned with the unravelling of the causes which must collaborate in producing the finished embryo (see p. 1.40). But the end of their domination was at hand, and the exsuccous Lord Chancellor, whose writings Harvey thought so little of, was making an attack on one of Aristotle's causu which was destined to be peculiarly successful. It is needless to quote his immortal passages about the "impertincnce,” or irrelevance, of final causes in science, for they cannot but be familiar to all scientific men.| Bacon demonstrated that from a scientific paint of view the final cause was a useless conception; recourse to it as an explanation of any phenomenon might be of value in metaphysics, but was pernicious in science, since it closed the way at once for further experiments. To say that embryonic development took the course it did because the process was damn on by a pulling force, by the idea of the perfect adult animal, might be an explanation of interest to the mcgaphysicim, but as it could lead to no fresh experiments, it was nothing but a nuisance to the man of science. Later on it became clear 315., am (he final cause was irrelevant in science owing to its ineJrpressibility in terms of measurable entities. From these blows the final muse ,m,e,. ,.m,,.md, 1,, Jgngmd the seventeenth century was the time of transition in these affairs, and in such books as Joseph Glannlle s.Plu.r Ultra and Scepsir Sdmfifica, for instance, or Thomas Sprnt’s Hula?of the Royal Sodely, the stonny conflict between the "netvzyor expenmental philosophy" and the Aristotelian "school-philosophy can easily be followed. Francis Gotch has given a delightful account of the cvgmng of Aristotelianism, but it involved 3 5101131)’ 5“m5¢'-3 afld 113*’ °ld°’ M535 did not give way wighgug 3 struggle. Harvey 3 work is perfectly representative of the period of transition. 701’. in his P’¢f3‘7° “1'd°"h°_h°3_"}11‘8 “Of the Method to be observed in the knowledge of Generation, _ he "Every inquisition is to be derived from its Causes, and clzxefly says‘ cut.” As for the formal cause, Bacon expressly excluded it from Physic, and it quietly disappeared as men saw that scientific laws depended on the repeatableness of phenomena, and that anything unique or individual stood outside the scope of science. Thus in the case of the developing eg, the formal and the final causes are scientifically meaningless, and if it were desired to express modern scientific discourse in Aristotelian terminology, the material and efficient causes would alone appear.

from the Material and Effici x D, Augrnenlxr Scimrinrmn, Bk. 1", eh. 4.

Aristotle alone was unharmed by Aristotelianism. A metaphysician as well as a scientific worker, he was able to use the concept of purposiveness as a heuristic aid, but he never rested upon it. The trouble was that he introduced it into the discussion at all. It is an interesting speculation to consider what would have happened if the first great biologist had not brought final causes into his teaching; perhaps the subsequent history of biology, and science as a whole, would have been very different. For final causes irresistibly led to the theological blind alleys into which men's thoughts were ushered and there left to grope till the end of the Middle Ages.

Perhaps Aristotle would not have made so many great discoveries if he had been more of 2 Democritus. For teleology is, like other varieties of common sense, useful from time to time; e.g. Harvey told Boyle that he was led to certain important considerations by meditating upon the final cause of the valves in the veins ;‘ and every biologist acts in the same way at the present time. But the important thing is not to give the last word to teleology. And those attractive shady places which Aristotle, guided by his genius, quickly passes through on his perpetual journeys into the hot sunlight of research and speculation were so many traps for those who followed him. He himself knew how to change rapidly from metaphysician into physicist and back again, how to bow politely to the final cause and press on with the dissection; but the later Peripatetics had no knowledge of this art, nor had the Patristic doctors, nor the mediaeval Aristoteliztns; who all remained sleeping quietly in the shade of the will of God. He knew very well from the sea (to use Bacon's metaphor at last) the look of the Circa country of teleology, but he never visited it for long at a time, being an authentic Odysseus, unlike so many later heads, who, following the example of Plato, “anchored upon that shore” and, dropping their hooks to the sound of plain-song, there rode, never to hoist sail again.

‘ The interview was related by Boyle in his “Disquisition about the Final Causes of Natural Things," x688—“And I remember that when I asked our famous Haney. in the only discourse I had with him (which was but 2 while before he dyed), \Vhnt were the thing: that induc’d him to think of I Circtxlatiorrof the Blood? He answer'd me, that when he took notice that the Valves in the Veins of to many Ievcml put: of the Body, were to Plzu:'d that they gave free passage to the Blood Towar_ds_the Heart, but opposfii the passage of the venal blood the Contrary vrpy: He was invited to imagine that so Provident a Cause as Nature had not no Plac :5 so many Valves without Design; and no design seemed more probable. than that._smce the llload could not well, betzuse of the interposing Valves, be sent by the Veins to the Lmbs; it Ihould he Sent through the America. and return through the veins. «hos: valves

did not oppose its course that way."

59 A msroxv or EMBRYOLOGY

13. The Hellenistic Age

Aristotle died in 322 no. From that year until 1534, the date at the binh 05 V°l°h=1' C031". first in time of the Renaissance cmhryologists. embryology has very little history.

The launder of the Stoic philosophy, Zeno of Citium, was born some twenty years before the death of Aristotle.

Pious and magmnimous as Stoicisrn was in the field of conduct [says Allbutt], creating or nourishing that elevation of mind which distinguished the nobler Roman of the Empire, yet in Rome, as in England, its natural science was of no account. The spirit of it was indeed rather alien than akin to science. The mind of the Porch which called itself “pr-actiail" was reluctant to all "speculation," natural science included.

The Stoics regarded the four qualities of cold, hot, wet and dry as ultimate, instead of the earth, fire, air and water of the Peripatetics and their predecessors. Plutarch. in his summary of philosophic opinions already mentioned, has some passages relating to their views on the development of the embryo.

The Stoiclrs say that the foetus is fed by the secundine and nu-ell; whereupon it is that midwives presently knit up and tie the navell string fast, but open the infants mouth, to the end that it be acquainted with another kind of nourishment.

And elsewhere,

The Stoicks say that it is a part of the wombe and not an animall by itselfe. For like as fruits be part: of trees, which when they be ripe do fall, even so it is with an infant in the mother's womhe. . . . The Stoicks are of opinion that the most parts are formed all at once; but Aristotle saith l.he backbone

and loina are first framed like as the heels in a ship.

But to which of Zcno’s successors-vcleanthes, Chrysippus, Crates or the rest~thcse sayings are to be attributed is not known.

The Epicureans also had opinions on these subjects. They thought that the foetus in utzra was fed by the amniotic liquid or the blood, and they also believed, in contradistinction to the Penpatencs, that both male and female supplied seed in generation, as is shown by the lines

usque adeo magni refert, ut sernina possint seminihus eominisceri genitaliter apta crassaque conveniant liquidis et liquida crasso.‘

But much more important than the teaching of these philosophers was the rise of what might be called the scientific faculty of the great University of Alexandria. That seat of lmrning, perhaps the most glorious, after Athens, of any in antiquity, and greater than its contemporary rival Pergamnn, was important because all the traditions of earlier times were united in it like a bimdle of strands coming together to form a rope. Democritean atmnism, Peripatetie science and metaphysics, Coan biology, Coan and Cnidian medicine, above all, Athenian mathematiés and astronomy, all were gathered in the povoeior of Alexandria under the benevolent dynasty of the Ptolemies. The link between the Alexandrian biologists and the school of Aristotle was Strata of Lampsacus, who, though apparently not making any contribution to embryology himself, must have brought the knowledge of generation gained by Aristotle to Alarandria as he sailed south across the Mediterranean to be the tutorofI’tolerny Philadelphus. The link between Cos and Alexandria was Diocles of Carystus, who was the last of the Hippocratic school and also a pupil of Philistion of Locri. Diocles has a certain importance in the history of embryology; for Oriliasius refers to him as die discoverer of the pmxttmn raliens in the mammalian embryo, "on the ninth day a few points of blood, on the eighteenth beating of the heart, on the twentyseventh traces of the spinal cord and head." He thus showed that the early development of chick and mammal was very alike. Plutarch also tells us that be occupied himself with the question of sterility. He described the human placenta, as well as embryos of twenty-seven and

‘ “A matter ofgreat moment 'tia in truth, That used may mingle rudily with seed Suited for pmcreatinn, and that thick _ Should mix with fluid seed, with thick the dim."

H5, 1257. For the further history of this view, which might also he called Hipptr crane. nee pp. 8o, r27, iso and :17. It could still be delended in the oeveiiteeiitli D€nn.rz_3" as by Kijpet and Mawricnu. _

Thu ispcihaps the place to refer to the fact, perhaps more singular than important, Ihatmassodarionbclweensnnllnnimah and themaleseedwurnadein antiquity. In I885 Ladelei figured a painted rnarhle sarcophagus in the rnuseuin at Tar-ngona, ouwhiehai-etwulnunanliguies in Minoan (7) costume, onemale, theodierferiiale. atnudingundertwudate—palma,ofwhiehoneiafernlea.ndtheoIhernoL Frpnit_he breastsot'thel'eriialethereooruesutreamofrniIk(asinthedevioeoftheunivei-rity ofCam'bridge);and[ruInthemaIeIstreamafseed.wLliidi,honeveniristg.doffaIIing naturally, curls Irmmd in a spin! (cf. the vortex diooriu satiriird by Aristophana in the Cloudr). Within this spiral many little animals are drawn. The_r= IS. Iinlortunately, do_ubt I.b0ul the authenticity of the sarcophagus, which might lllIln'0d._ul€l1 be di.i— mixedvrereitnoxforthestnry,foundinIevn1lGrcekauthm:,e.g.mtheaeeond oenniry, Antoninus Liberalia, that the need of Minot contained all wm_oi noxious annuals (snakes, scorpimu Ind Ieulopeudru). As a result all his lover: died until he u-an:uru‘lbyProcria. Ct'.A. B. Coolr,vol. zpp.2, rzrr.

[0117 dflfs. and he held that both male and female contribute seed in Bfilcnition. Cnidian medicine influenced Alexandria through Chrysip-

25 0;i.It'id‘i].:—t]i1cst the SIOit‘.—$Vltt)Se embryologieal doctrine seems to ve t t e embryo had only a vegetative sou] until birth or hatching.

All these influences were fruitful, for they produced the two greatest physiologists of ancient timt-.s—Heropiiilus of Chalcedon and Emistxatus of Giios. These two, who were contemporaries during the third century B.c., experimented much and wrote volurninously, but all except fragments of their writings have been lost, and can now only be pieced together out of the books of Galen, as has been done by Dobson. Allbutt has well described the dilferericcs between them, such as the predilection of Herophilus for the humoral pathology and pharmacy, and the grater interest taken by Erasistrams in atomistic speculations. "Herophilus," says Plutarch, “leaveth to unborne babes a moovin naturall, but not a respiration, of which motion the sinewes be thi

\ instrumentall cause, but afterwards they become perfect living animall creatures, when being come forth of the tvnmbe, they take in breath from the sire."

Herophilus described the ovaries and the Fallopian tubes, but did not add no further than Aristotle towards correct sexual physiology in this respect. \Ve gather that he made many dissections of embryos from the testimony of Tertullian, though this may not be worth much. Moreover, he called the outer membrane of the brain, chorion, after the membranes which surround the embryo. He gave a Dorrect description of the umbilical cord, except that he assigned to it four vessels instead of three, carrying blood and breath to the embryo. The veins, he thought. coinmunicated with the venae cavae, and the arteries with the great artery running along flu spine. Hcrophilus also occupied himself much with obstetrical matters, and wrote a treatise on them, iuim.-rmfv. Together u-ithEi-asistntushe denied that there were any diseases special to women other than those attendant on their special sexual {LlnCllOnS,.l3tIf the greatest contribution which he made to biology was the association of the brain with the intellect,‘ for even Aristotle had made the heart the eat of the mental individual.

Ensistratus did not study embryology as much as H5"-}Ph'J“3: hm

a passage in Gala: throws an interesting light on his notions of em-

bryonic growth. The heart ' larger at fiist than a millet seed, or, ifyou ‘lih, =1 b€1"~ Alk Y°’||‘3¢“ hflwlitntilouid grow large otherwise than by being distended and re-

‘ This wu not Ihsolutdy new: Alumeon had held the same sicw (lee Eu-rnztl 62 CHART II

zeiving nutrimettt throughout its whole cxtcnt, just as W: hat: shown Ibovg that the seed is nourished. But even this is unknown to Emsistratus who makes so much of Nature’: Art. He supposes that animal: gmw jun like , 3|9V¢._3 f01f€._=| bag. Of '3 bfisktt. etch of “rl'HCl'l grows by the addition to it of matcnals sumlar to those out of Wllltil it began to be made.

This is only_onc instance out of many in which Galen the teleulogist finds fonlt with Ernsistmtus the mechanistic philosopher.

'Dur-mg the period when the biological school of Alexandria was at its height, that city became an important Jewish centre. Two centuries later It was to produce Philo, but now the Alexnndrian Jews were writing that part of the modem Bible known as the Wisdom Literature. In books such as the Wr'm'om of Solomon, Ecrlti-z'a:I:'¢-ur, Proozrlu, etc. the typiml Hellenic exclusion of theaction of godsin natural phenomena is clearly to be seen. There are two passages of cmbryological importance. Firstly, in the Book of ]ab (x. to), Job is made to say,

Remember, I bcsccch thee, that thou hast fashioned me as clay; and wilt thou bring me into the dust again? Host thou not poured me out as milk, and curdlcd me like cheese? Thou hast clothed me with skin and flah, and knit me together with bones and sinews.

This comparison of embryogcny with tho making of cheese is interesting in view of the fact that precisely the same comparison occurs in Aristotle’s book On the Generation of/1nx'maLr, as we have already seen.‘ Still more extraordinary, the only other erubryological reference in the Wisdom Literature, which occurs in the Wim'om of Solomon (vii. 2), also copies an Aristotelian theory, namely, that the embryo is formed from (menstrual) blood. There the speaker says. "I" “I5 “V1115 0f 3 mother rm: I moulded into flesh in the time often months, being cornpacted with blood of the seed ofman and the pleasure accompameth sleep." Perhaps it is no coincidence that both these citations can be referred back to Aristotle, and in the second case Even I0 H'PP°°““_°5i perhaps the Alexandrian Jews of the third century B-cwere smdrmg Aristotle as attentively as Philo Judaeus studicd Plato 3 C°UPl¢ °f hu-;;:gJi:::d:;r;chw1. was dimcrly responsible for the introduction of Greek medicine and biology into Raine, through the physician Clcophxntus, who seems to have lice“ P“m°‘d“Iy mmhrcssedfn 3:? cology. At the end Zr «trite sfiefsond §:;ng;n!::hEr£n:?;idms ' e t e an ' firs‘, Rome race“ ht atnrnism with him. H: W33 \h\13

Asclepiades of Parion, who broug . . _ _ ghe fink bggwecn Epicurus and the methodisuc school Of PhY5“71‘“"‘md

may have been a potent influence upon Lucretius. Again, Alexander Philalethes provides the link between Cleophantus and Saranus. Soranus lived in Rome from about A.D. 30 till just after the end of the first century, and so twenty years before the birth of Galen.

Of all the ancient writers on embryology Sormus is the one whose works were in later times most widely appropriated, mutilated, furbished up, quoted from rightly and wrongly, and generally upset. Allbutt, Barbour and Singer give accounts of the way in which this process went on, and the whole question has given rise to a considerable literature (see Lachs, Ilberg, Sudholi, etc.). It lasted right into the Middle Ages, and was particularly vehement in the case of the treatise on gynaecology, neg! yvI'au¢st’aw na0u'n'. This was translated into Latin under the name of Moscbion, then back into Greek and finally back into Latin again. It is largely obstetrical, but it shows an advanced knowledge of embryology, and especially an accurate idea of the anatomy of the uterus. (See Plate III, facing page 66.)

Mention may here be made of a woman writer, Cleopatra, whose short treatise on obstetrics was often reprinted in the collective works of the Renaissance (Bauhin and Spach, q.v.). She appears to have been

1 sensible gynaecologist contemporary with Soranus and Galen (cf. the papers of Hurzl-Mead). At the time of the first publication of the present work, my friend Dr R. W. Gerard brought to my notice a curious story, the origin of which he was unable to trace, that Cleopatra, the Ptolemaie queen, had investigated the process of foetal development by the dissection of slaves at known intervals of time from conception, following the precepts of Hippocrates with regard to hen‘s eggs. The story is, it seems, Rabbinic (cf. Preuss, p. 451). R. Ismael (Nidd. tn. 7) taught that the male foetus was complete in 41, the female in 8r, days, and cited as his authority the results of the above Alexandrian experiment. Sceptics urged that copulation might have taken place before the experiment began, but supporters replied that an abortifacient was, of course, given.

Sceptics begged leave to doubt the universal efficiency of these drugs. They also questioned whether intercourse between the slaves and the prison guards had been absolutely guarded against.

The whole subject is not as absurd as it seems at first sight, for it provides an example, in the Hellenistic or Patristic period, not common perhaps even in the Talmud, of a serious discussion on scientific method. and the planning of an experiment. It demonstrates how near men could come to the Baconian outlook. Other considerations, economic and theological, such as those referred to in the introduction to the present work, demonstrate how for men really were from it. It may be proper to point out here that the Hellenistic, as opposed toythagslhtlg: mediaeval and post-mediaeval, arguments about “perfection.g1men were related to a quite serious scientific problem, namely the respective part played by growth and difl'erenti.-itian in development. These concepts were clear in Aristotle's mind (see e.g. p. 52) and it was legitimate to investigate their speeds and end-points. The theological aspect of the subject was secondary.

‘ A iimtlar story is found in Chinese legend eonwrning one of the early kings. Particulars will be found in the author’: Science and Civuliralinn in china. ml. 8.

Whether the story itself rests upon a confusion between Cleopatra the gynaecologist and Cleopatra the queen, or whether it arose entirely in R. Ismael's imagination, cannot at present he decided.

The other writers of this period are unimportant emhryologically. Among the Greelis, Aelian wrote a De natimz urzimalium, in which 11¢ spoke of eggs, but without adding anything to our knowledge of them. Nicander in his T herfaco refers to mammalian embryos, and alleges that they breathe and eat through the umbilical cord, and Oppian has a few unsystematic remarks about the embryos of various animals. Junius Colume1|a's work on husbandry contains two chapters on eggs} but he was not much interested in the theoretical aspect of development. In Aulus Gellius we have the cheese analogy appearing in conjunction with obscurantist views about the powers of the number seven.‘ It is not generally known that a clear statement of the preformationist or "Entfaltung" theory of embryogeny' occurs in Seneca’s Quaerlimiu Natumles, where there is the following passage:‘

In the seed are enclosed all the par: of the body of the man that shall be fanned. The infant that is borne in his mother’: woinbe bath the routes of the bard and hair that he shall weare one day. In this little masse likewise are all the lineaments of the bodie and all that which Posterity shall discover in him.

Perhaps this notion was derived by Seneca {rain the Homoeorriereity of Anaxagums, for a discussion of which m relation to embryology, see comfm-d, “Hair cannot come out ofnot-hair, nor flash out of not-flesh,”

said Anaxagoras.' ’ Bk. in. ch. in.

I Bk, v-m, ch 5. . ,m_ 16 mdmft ‘Bk. m.ch19. . I §;°.°i,,P”,,.iv point7s out um mother link in the obscure early ehiun of pieromuuan. . v m 5. found In St Augustine, as quoted zxpreuly on the pain: by Vanu'“ ‘.’‘E‘‘"‘‘‘ ‘’ ,,, ma smtllntnl or Homoeornereiry any, n rim, be aiiiimi to . ’‘"“’‘-'7’‘’‘ E?‘ 4:33,. shable Iron-i TcnnysDn': "flower in on emiiiied wait" “mama-h ¥ori oi sgiuiauguiunea idus is an: of Meyer; in mm them Wk '° T" W: 5ms«iiucdof the swim who regarded thae ieeai of things I! m mi: A ll.

lfleyer describes Ill: views of mic mi of many Pilréllfit whim such 85 Justin _Mmyi, C|:m:nthof§\le_x1n‘:lri2.'°Y;%95’:n'e:“ grggzgung gm regards Augustine I: linked to e tom Y w Y ~ 66 ' PLATE HI

.G7n]a:.;uuC.Y no pm gunning fu (wyw uaypxnm xjmmg :1]; ) '5”

Mruun-q/um v mru_.] mum am /b lmpuup uamuq mp“) nu

The Natural History of Pliny, that “volu.mi.nous, industrious, unphilosophical, gullible, unsystematic old gossip,” as Singer justly calls him, contains little of embryological importance, although he devotes many sections to eggs, and what there is comes straight from the fountain-head, Aristotle. As, for example,

All egs have within them in the mids of the yolk, a certain drop, as it were of bloud, which some thinke to be the heart of the chicken, imagining that to be the first that in everie bodie is formed and made; and certainlie a man shall see it within the verie egge to pant and leape. As for the chick, it taketh the corporal] substance, and the bodie of it is made of the white watexish liquor in the eggs, the yellow yoll-Le serves for nourishment; whiles the chick is unhatched and within the egge, the head is bigger than all the hodie besides; and the eies that be compact and thrust together he more than the verie head. As the chick within growes bigger, the white turneth into the middest, and is enclosed within the yolke. By the 20 day (if the eggs be stirred) ye shall heare the chieke to peepe within the verie shell; from that time forward it beginneth to plume and gather feathers; and in this manner it lies within the shell, the head resting on the right foot, and the same head under the right wing, and so the yolke by little and little decreaseth and fnileth.

But the best way to illustrate Pli.ny's embryology is to copy out some of his index, as follows:

The Table to thefim T om: afPIx'niu Na!umllH1':ton’:

Egs diverse in colour ‘* , 298 Egs of birds of 2 colours within the shell ibid. , Egs of fishes of 1 colour ibii Egs of birds, serpents, and fishes, how they differ ibid. Egs best for an hen to sit upon :99 Egs hatched without a bird, onely by a kind heat ibid. Egs how they be marred under an hen ibid. wind—egs, milled Hypenemia goo how they be engendered 301 wind-egs, Zephyria ibid. Egs drawn: through a ring ibidEgs how they be best kept ibidthe serpents egge, which the Latines call Anguinum, what iris, and how engendered 3 53

This last item exhibits Pliny at his worst. It is worth quoting, apart from any intrinsic value, for it shows to what depths ernbryological

above) und. Cicero, who in the De Nntum Dzonrm makes one of his char-Aden outline the Stoic doctrine of needs.

The devious connections between Greek etornism and seventeenth-century biolozxal preformariomsrn are new fairly clear (see 1331:: Ind also the note on the Kabbelah, p. 79). But otherwise excellent histories of Itamisrn, luck as that of Gregory. gitecxyump direct from Epicurus to Gzssendi, entirely neglecting the stoic-Kabbahm:

knowledge descended within four hundred years after Aristotle collected his specimen: on the she 1' th la 1' with the fishermen of l\litylene.' ms 0 E goon O Pynha' and talked

I wiIl'not averpasse one kind of eggs besides, which is in great name and request in France, and whereof the Greek: authors have not written a word‘ and this is the serpents egg, which the Latins call Anguinui-n. For in summe; _time yerely, you shall see an infirut number of snakes gather round together into an heape, entangled and enwrapped one within another so artificially as I am not able to exprnse the manner thereof; by the means therefore of the froth or salivation which they yeeld from their mouths, and the humiiur that eunimeth from their bodiu, there is engendred the egg aforesaid. The priest: of France, i-alled Druid.1e,' are of opinion, and so they deliver it, that thue serpent: when they have thus engendred this egg do cast it up on high into the aire by the force of their hissing, which being observed, there must be one ready to card: and receive it in the fall again (before it touch the ground) within the lappet of a coat of arms or souldiour: mssoclrs. They afiirine also that the party who mrrieth this egg away, had need to be we] mounted upon a good horse and to ride an ay upon the spur, for that the foresaid serpents will pursue him still, and never give over until they meet with some great river betiveene him and them, that may cut off and intercept their ehace. They ad moreover and say that the only mark: to know this egg whether it be right or no, is this, that it will swim aloft above the water even against the stream, yet: though it were bound and £l'lC.l'L'LIBd with a plate of

gold. Hut one must not be too_se\'ere upon Pliny, for he and his translator,

Philemon Holland, provide unequalled entertainment.

To some atent the same applies to Plutarch of Chaeroiiea, who lived about the same time. Plutarch’s uritings, inspired as they were throughout by the desire to commend the ancient religion of Greece to a degenerate age, represent no milestone or turning-point in the history of embryology, yet there is a passage in the Spnpntiaguu, or Table-guextxbnr which bears upon it. The third question of Book II is “Whether was

before, the hen or egg ?"

This long time [says Plutareh] I absteined from eating eggfs, by mason 05 a certaiiie dream I had, and the oomparue conceived an opinion or suepition of me that there were entred into my head the fantasies and superst-ItI0‘ns 0; Orpheus or Pythagoras, and ihat‘I abhorred to_eat an egge for that I beheie it to be the principle and fountain: of gEn=mtl°n«

He then makes the various characters in the dialogue speak to the m0‘ lion, and one of them, Firmus. ends his speech thus, 5 d’Arey Th , . . .

ipfj. ;,,,.,,,, ;,,{,"’,..‘,’,’,‘Z§Z,. .y,._,.., the serpent: eggs of the Druidx, m lxemiricli.

12. rest they were probably {mil eelunodcgim

And now {or that which remaineth (quoth he and therewith he laughed) I will sing unto those that be sltilfull and of understanding one holy and sacred sentence taken out of the deepe secrets of Orpheus, which not onely importeth this much, that the eggs was before the henne, but also attributeth and adjudgeth to it the right of eldership and priority of all things in the world, as for the rest, let them remaine unspoken of in silence (as Herodotus saith) for that they bee exceeding divine and mystical], this onely will I spealre by the way; that the world containing as it doth so many sorts and sundry kinds of living creatures, there is not in manner one, I dare well say, exempt from being engendred of an egge, for the egge bringeth forth birdes and ioules that flie, fishes an iniinit number that swimme, land creatures, as lizards, such as live bath on land and water as crocodiles, those that bee two-footed, as the bird, such as are footlesse, as the serpent, and last of all, those that have many feet. as the unwinged locust. Not without great reason therefore it is consecrated to the sacred ceremonies and mysteries of Bacchus as representing that nature which produoeth and eomprehendeth in itself: all things.

This emphatic passage looks at first sight as if it was a statement of the Harveian doctrine ormre uivznn ex am.‘ But the fact that no mammals are mentioned makes this improbable.‘ Fir-mus then sits down and Senecius opposes him with the well-worn argument that the perfect must precede the imperfect, laying stress also on the occurrence of spontaneous, i.e. eggless, generation, and on the fact that men could find no "row” in eels. Three hundred years later, Ambrosius Macrobius‘ handled the question again in his Satumalia,‘ and the progress in emhryological knowledge could be strikingly shown by the difference in treatment. It would he an interesting study to make a detailed comparison.

14. Galen and the Vital Faculties

Another fifty years brings us to Galen of Pergamos, second in greatness among ancient biologists, though in spite of his multitudinous writings he does not quite take this high rank in embryology. That knowledge of the development of the foetus was at this time specially associated with Peripatetic tradition appears from a remark of Lucian of Samosata, Galen's contemporary. In the satire called The Auction a_/tire .Ph:’Iarophz'2:, Hermes, the auctioneer, referring to the Peripatetie who is being sold, says, "He wil.l tell you all about the shaping of the embryo in the womb." But Galen was now to weld together all the biologiul lmowlcdge of antiquity into his voluminous works, and so transmit it to the Middle Ages.

5_ec on, p. 133 ff. Frrmus wu doubtless referring to the cosmic egg of Orphie speculation, see p. :7. ' See “flxittalter, p. 56. ‘ Ch. 7.

59 A rusrorzr or zmmronoar

Mm "7 G=1¢“'5 Wmmg Was done between A.D. X50 and x8e. Out of the twenty volumes of Kuhn’: edition of 1829, less than one is concerned

embryology, a proportion considerably less than in the case of Aristotle. Galen‘: emhryology is to be found in his zuol ¢oaum‘nr Jordpcwv, On tluNuIunzl Familiar, which contains the theoietical part, and inhis On theForma!x'on aftlu Fnelm‘, which contains the mom ammmicaj Pam Tlllfe i! also the probably spurious treatise :2 tzgsov 16 mm‘: ymargde, On the Querlion afu-lzetlter the Embryo 1': an /1m'maI.l

It IS important to realise at the outset that Galen was a vitalist and a teleologlst of the extreme kind. He regarded the living being as owing all MS characteristics to an indwelling physis or natural entity with whose "faculties" or powers it was the province of physiology to deal. The living organism aooording to him has a kind of artistic creative power, a t£zn[, which an on the things around it by means of the facultiu, dc.-ra'p:L;, by the aid of which each part attracts to itself what is useful srnd good for it, 25 olxeiov, and repels what is not, -rd dudrgtov. These facultis, such as the “peptic faculty" in the stomach and the “sphygmic faculty" in the heart, are regarded by Galen as the muses of the specific functions or activity of the part in question. They are ultimate biological tztegories; for, although he admits the theoretical possibility of analysing them into simpler components, he never makes any attempt to do so, and evidently regards such an effort as doomed to failure, unlike Wilhelm Roux, whose "interim biological laws" were really conceived of as intuim.

The effect: of Nature [says Galen] while the animal is still being formed in thewombare all the different parts of the body, and after it has been born an elfeet in which all parts share is the progress of each to its full size and thereafter the maintenance of itself as long as possible.

Galen divides the effects of the faculties into three, genesis, growth and nutrition, and means by the first what we mean by embryogeny.

Genesis is not a simple activity of Nature, but is compounded of alteration and of slurping. Thatis to say, in order that bone, nerve, veins and all other tissues may come into existence, the underlying substance from which the animal spring: must be altered; and in order that the substance so altered my ,gq..;.¢ 5;; appropriate shape and position. in eauritics, outgrowths, and atudunents. and so forth, it has to undergo ashapmg or formative prooim. One would be justified in falling this substance which undergoes alteration the material ohnanimal,just as wood is the material or‘: ship and wax ofam

Image. 1 yo, .. uulyti: of the view: of Galen on heredity, rec mks (I934)-

This is a very remarkable passage. Galen’s words express quite modern views about growth and differentiation. They are also applicable to our current distinction between chemical and histological differentiation on the one hand, and morphogenesis an the other.

Galen then goes on to treat of embryogeny in more detail.

The seed having been cast into the womb or into the earth—for there is no difference-—[he says (see p. 44)] then after a certain definite period a great number of parts become constituted in the substance which is being generated; these differ as regards moisture, dryness, coldness and warmth, and in all the other qualities which naturally derive therefrom [such as hardness, softness, viscosity, friability, lightness, heaviness, density, rarity, smoothness, roughness, thickness and thinness]. Now Nature constructs bone, artilage, nerve, membrane, ligament, vein and so forth at the first stage of the animal's genesis, employing at this task a faculty which is, in general terms, generative and alterative, and, in more detail, warming, chilling, drying and moistening, or such as spring from the blending of these, for example, the bone-producing, nerve«praducing and cartilage-producing, faculties (since for the sake of cleamess these terms must be used as well). . . . Now the peculiar flesh of the liver is of a certain specific kind, also that of the spleen, that of the kidneys and that of the lungs, and that of the heart, so also the proper substance of the brain, stomach, oesophagus, intestines and uterus is a sensible element, of similar parts all through, simple and uncompounded. . . . Thus the special alterative faculties in each animal are of the same number as the elementary parts, and further, the activities must necessarily correspond each to one of the special parts, just as each part has its special use. . . . As for the actual substance of the coats of the stomach, intestine and uterus, each of these has been rendered what it is by a special alterativo faculty of Nature; while the bringing of these together, the combination therewith of the structures that are inserted into them, etc., have all been determined by a faculty which we all the shaping or formative faculty; this faculty we also state to he :u'tistic—nay, the best and highest art—doing everything for some purpose, so that there is nothing ineffective or superfluous, or capable of being better disposed.

Thus the alterative faculty takes the primitive unformed raw material and changes it into the different forms represented by the different tissues, while the formative faculty, acting teleologically from within, organises these building-stones, as it were, into the various temples which make up the Acropolis of the completed animal. Galen mutt goes on to speak of the faculty of growth. "Let us first mention,” he says, "that this too is present in the foetus in were as is also the nutritive faculty, but that at that stage these two faculties are, as it were, hand~ maids to those already mentioned, and do not possess in themselves supreme authority."

Later on, until full stature is reached, growth is predominant, and finally nutrition assumes the hegemony.

So much for Galen's embryological theory. But before leaving the treatise On the Natural Faculties, it may be noted that he ascribes a retentive faculty to the utems as well as to the stomach, and explains birth as being due to a cessation of action on the part of the retentive faculty “when the object of the uterus has been fulfilled," and a coming into action of a hitherto quimcent propulsive faculty. This wholesale allotting of faculties can obviously be made to explain anything, and is eminently suited to a teleological account such as Galen’s. It was not i.noonvcnient as a framework within which all the biological knowledge ofantiquity ctvuldbe crystallised, but it was utterly pernicious to experimental science. Fifteen hundred yggjs later it received what would have been the death-blow to any less virile theory, at the hands of Moliere in

his immortal Illalmie Imuginaire:

Badulirriu. Mihi 3 docto doctor: Demandatur causam et ratianem quare

Opium tacit dorrnire A quoi respondeo Quia est in ca Virtus dormitiva Cujus est nature Sensus assoupire

Charla. Bene. bane, bene, bcne respondere. Dignus, dignus est eutrare In nostro docto oorpore. Ilene, beue, respondcrc.‘

But to return to Galen. The book an the fonnation of the embryo opens with a historical account of the views of the Hippocratic writers with whom Galen was largely in agreement. It goes on to dscribe the anatomy of allantois, amnios, placenta and membranes with considerable accuracy. The embryonic life consists, it says, of four stages (5) an uniormed seminal stage, (2) a stage in which the trio prinapxrt (a concept here met with for the first time) are engendered, the heart. hm’

‘ Bduloi. The learned doctor tab

The cause and reason deep why opium tends to llezp _ To him I make reply nfiim\=,U,\'= liususe ir has 1 wine dormmv: And can our lenses lulL

c;..... r. I didl " ii;‘.’;i.'.”véon°»?§‘:l’."2=?.'Zx‘;‘?J§.'.‘é’.rf3' shows mi. knowledge To enxer the Phy-:iu'nru' learned College.

and brain, (3) a stage when all the other parts are mapped out and (4) a stage when all the other parts have become clearly visible. Parallel with this development, the embryo also rises from possessing the life of a plant to that of an animal, and the umbilicus is made the root in the analogy with a plant. The embryo is formed, firstly, from menstrual blood, and secondly, from blood brought by the umbilical cord, and the way in which it turns into the embryo is made clearer as follows: "if you cut open the vein of an animal and let the blood flow out into moderately hot water, the formation of a coagulum very like the substance of the liver will be seen to take place." And in efl"ect this viscus, according to Galen, is formed before the heart.

Galen also taught that the embryo excreted its urine into the allantois. He was acquainted with foetal atrophy. He gave a fairly correct account of the junction of the umbilical veins with the branches of the portal vein, and the umbilical with the iliac arteries, of the faramen nvale, the duclus Arantii and the ductu: Bolalli.‘ He maintained that the embryo respired through the umbilical cord, and said that the blood passed in the embryo from the heart to the lungs and not vice t/zrm. The belief that male foetuses were formed quicker than female ones he still entertained, explaining it as being due to the superior heat and dryness of the male germ. He also associated the male conception with the right side and the female with the left and asserted that the intra-uterine movements are sooner felt in the case of the male than in that of the female. Dry foods eaten by the mother, he thought, would lead to a more rapid development of the foetus than other kinds.

In this account of the Galenic embryology I have drawn not only upon the book on the formation of the foetus, but also upon his t51ld[lV1]}lt1, Commentary on Hippocrates, his nsgl airiaw crv/mrmgzciraw, On the Caurex of Symptoms, and his book negl zgtfag -nfiv pwgfwr, On the Use of Parts. It is this latter work that had the greatest influence on the ages which followed Galen's life. In the course of seventeen books, he tries to demonstrate the value and teleological significance of every structure and function in the human and animal body, and to show that, being perfectly adapted to its end, it could not possibly be other in shape or nature than what it is. At the conclusion of this massive work with all its extraordinary ingenuity and labour, he says,

Such then and so great being the value of the argument now oompleted, this section makes it all plain and clear like a good epode, I say an epodc, but not in the sense of one who uses enchantmenm (énqioafg) but as in the melic poets whom some call lyric, there is as well as strophe and antistrophe, an

‘ Whether Galen knew of the durtux venom: Franklin considers doubtful. 73 A HISTORY or rzmmrowar

‘W59: Which» 50 1'! 1'3 Said. they used to sing standing before the altar as a hymn to the Gods. To this when I compare this final section and therefore I have called it by that name.

T:h15 is one of the half-dozen most striking paragraphs in the hggmy of biology; worthy to rank with the remarks ofldippccrates on the "sacred disease."| Galen, as he wrote the words, must have thought of the altar of Dionysus in the Athenian or Pergamene theatre, made ofmarble and hung about with a garland, but they were equally applicable to the altar of a basilica of the Christian Church with the bishop and his priests celebrating the liturgy at it. What could be more charged with significance than this? At the end of the antique epoch the biology of all the schools —Crotom, Aerag-as, Cos, Cnidus, Athens, Alexandria, Romeis welded together and as it were deposited at the entrance into the sanctuary of Christendom. It was the turning-point, in Spenglefs terminology, between Apollinian civilisation and Faustian culture. Galen’s Words are the more extraordinary, for he himself can hardly have foreseen that the long line of experimentalists which had arisen in the sixth century B.C. rmuld come to an end with him. But so it was to be, and thenoefonvard experimental research and biologiml speculation were alike to cease, except for a few stray mutations, barn can of due time, until in r453 the city of Byzantium should burst like a ripe pod and distributing her scholars all over the West help to bring all the fruits of the Renaissance, as if by a fertilizing process, into being. as even u do other diseases. Men regard its nature as divine from ignorance and wonder. since it is 1 peculiar tondltian and not any understood. Yet if rt be reckoned drvuae merely beause it is wonderful, then irutetd of one‘ there should be marry Iacrcd diam”. . . . The «cred diseae trials like Ill other dueme: from dung: which enter and quit the body, Iueh 1: cold, the um. md rhe winds, Whldl are rresern rest Ind are

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‘hing: gre dike drxine crud all thing: are able human."