Anatomical exercitations concerning the generation of living creatures to which are added particular discourses of births and of conceptions, &c. / by William Harvey ...

Of the Generation of Vivi∣parous Animals. (Book 63)

EXER. LXIII. (Book 63)

THus farre have we proceeded in the Generati∣on of Oviparous Animals; it follows, that we now produce our Observations, concerning the other species of Viviparous productions: wherein we have found very many things which are alto∣gether the same with those which occurre in the Egge; which we have reduced hither to be con∣sulted, and come last to be delivered. Which, though they are paradoxical, and run counter to the common received tenets, yet are they, if my judgment fail me not, entirely consonant to the Truth.

Amongst Viviparous Animals, Man is the chief, and most perfect of all: next him (that we may proceed from such as are more known) are ranked those creatures that are more sociable & obvious: (whereof some are solidipeda, whole-hoofed; as the Horse, and Ass: some are Bisulca, cloven foot∣ed; as the Oxe, the Goat, the Sheep, the Hogg, and the Deer: others fissipeda, sive digitatis pedibus, Creatures whose feet are distinguished into Toes; as the Dog, the Cat, the Cony, the Mouse, and the like; out of the manner of whose generation, we may conclude concerning the generation of all o∣ther Viviparous Animals. Wherefore, (as we have done in the History of the Egge, so) we shall single out some one kinde of these, as an Exemplar or Representative of all the rest; which, as being most known to us, will give light to the rest, and

become a platform, to which all the other may be reduced, by way of Analogy.

I have already given you the reason, why I have drawn out documents concerning all other Egges, from the Egges of Hens: namely because those are cheap, and every mans purchase; and upon that score we our selves had the advantage to make the more diligent disquisition, and o∣thers also have the better opportunity to experi∣ment the truth of our doctrine.

But there is more difficulty in the search into the Generation of Viviparous Animals: for we are almost quite debarred of dissecting the humane U∣terus: and to make any inquiry concerning this matter, in Horses, Oxen, Goats, and other Cattel, cannot be without a great deal of paines and ex∣pense. But those who are desirous to make tryal, whether we deliver truth, or not, may assay the business, in Doggs, Conies, Cats, and the like.

Fabricius ab Aquapendente, as if every Viviparous conception were a kind of egge, begins his Tract with that; (as being the general exemplar of Generation) giving this amongst other, as the chief ground of his proceedings; namely, because the contemplation of the egge, is of the largest extent: * 1.1 for the greatest part of Animals, saith he, is genera∣ted out of Egges. But we in the entrance of these our Observations, have concluded that all Ani∣mals are in some sort produced out of an Egg: For the foetus of Viviparous creatures is produced after the same manner and order out of a pre-existent conception, as the Chicken is formed and consti∣tuted out of an Egge: There being one and the same species of generation in them all, and the ex∣ordium or first principle of them all is either called an egge, or at lest something answerable and pro∣portionable

to it. For an Egge is an exposed con∣ception from which a Chicken is produced; but a conception is an egge retained within, untill the foetus have attained its just bulk, and magnitude: in other matters it squares with an egge: for they both are Vegetal rudiments, and also Animals in po∣tentiâ. Wherefore the same Theorems, and Corolla∣ries, (though contrary to the received perswasion) which we have already inferred in the History of the Egge, are most true: Likewise of the genera∣tion of all kind of Animals. For it is a confessed and plain thing, that all foetuses, even humane ones also, are procreated out of some conception, (or certain ground-work.) And this is also as true: that that thing which is called Primordium, the first rudiment in spontaneous productions, semen, the seed in Plants, and Ovum the Egge, in Oviparous (as being that corporeal substance, out of which moving and operating by an intrinsecal principle, that which is produced is either a Plant or an A∣nimal:) that same thing in the Generation of Vi∣viparous Animals is conceptus primus; the first Con∣ception: and this is approved to be true both by sense and reason.

What we have formerly affirmed of the egge, namely, that it is the sperme and seed of Animals, proportionable to the seed of Plants: the same do we now pronounce of the conception, which is the reall seed of Animals, and therefore also called An Egge. For that is true seed according to Aristotle, * 1.2 which takes its Original from two Animals joined in coition; and obtaines the virtue or power from both Sexes; such is the seed of all Plants, and of some Animals which know no distinction of Sexes: as it were that which is first mixed from. Male and Fe∣male, being a kind of promiscuous conception, or Ani∣mal:

for these creatures have that in themselves alone, which is required of both Sexes: namely, a fit mat∣ter to feed the foetus, and also a plastical, or forma∣tive, and operative vertue able to produce it. So in like manner, the conception is the fruit of the Male, and Female joined in coition, and also the seed of the future foetus; wherefore it differeth not from an egg.

But that, which proceeding from the Generant, is the cause which first obtains the principle of Generation * 1.3 (viz. the Efficient) ought to be called the Geniture, but not the seed (as it is miscalled by the common people, and Philosophers too at this day) because it hath not in it that thing which is required of two in coition, neither is it proportionable to the Seed of Plants. But whatsoever doth possess the foresaid condition, and is answerable to the Seed of Plants, that also doth deserve to be called an Egge, and a Conception.

Also the definition of an Egge, delivered by A∣ristotle doth fully square to it: saying, An Egge is * 1.4 that thing in perfect productions of part whereof an Animal is made, and susteined by the remainder, af∣ter it is made. Now the same things agree to a Conception, as shall afterwards appear by the dissection of Viviparous Animals, our Eyes them∣selves being witnesses thereunto.

Besides, as a Chicken is hatched out of an Egg, by the fostering heat of the Sitting Hen, or some other ascititious hospitable patronage, so also the Foetus is produced out of the conception in the egge, by the soft and most natural warmth of the parent.

In a word: that which Oviparous Animals afford by Incubation, or gathering under their Wings and Breast; that is exhibited by Viviparous, by the

Womb, and neerest, or inward embraces. And then, concerning that which relates to procreati∣on, the foetus is produced out of the Conception, in the selfe same manner, and order, as the Chic∣ken out of the Egg; With this onely difference, that in an egge, whatsoever relates to the Consti∣tution and Nutrition of the Chicken, is at once conteined in it: but the conception (after the foe∣tus is now formed out of it) doth attract more nourishment out of his Parents Womb; whereup∣on the nourishment increases with the foetus. More∣over the Egge is quite emptied, when the Chic∣ken is grown; and the Aliment which was in it consumed, nor doth the Chicken attract any more sustenance from the Hen: but the Oviparous Foetus doth still finde out fresh supplies, and su∣steineth it self by Milk.

Now the Eggs, or Spawn of Fishes are suppor∣ted by food procured from without; the Egges of Insects also, whether they have shells or not, have their provisions from abroad, nor are they lesse eggs for that, either really, or nominally: so in like manner the Conception deserves the title of an Egge, though it be susteined by a various kind of Aliment from without.

Why some Animals are Oviparous, and all do not produce their Foetus alive, Fabricius offers this reason: namely, because egges (if they were de∣tained in the Uterus till the Pullus were hatched) would by their weight prejudice the flight of Birds. And also in Serpents, or creeping things the multitude of egges would be an impediment to their winding motions. Nor is there compass enough in the narrow circuit of the Snailes shell, to afford room to the number & increase of eggs. So likewise the Fishes bellies are too scanty to

contein their numerous Fry, should they grow within them. And therefore these several crea∣tures are inforced to exclude their births, ere they arrive to perfection. So that it seems most natu∣ral for an Animal, to contein and cherish its con∣ception within it self, untill the foetus be quite perfected: but nature is sometimes constrained to expose her issues immature, and imperfect, and to compleat them with provisions sought for from without.

For as much therefore as concerns procreation, All kind of Animals are generated after the same manner out of an Egge-like Rudiment: (which we call Egg-like, not that every Rudiment of an A∣nimal doth resemble an Egge in Figure, but in Nature and Consistence) For in all their respe∣ctive Generations this they have in common, name∣ly, that a certain Vegetal principle is pre-existent (of like nature to an Egge, and answering in proportion to the Seed of Plants) out of which the foetus is produced. And this Egg or Egg-like substance is in them all, possessing the nature and conditions required in an Egg: which conditions also the seeds of Plants have common to them, as well as Animals. And for that cause the princi∣ples of any kind of Animals, are called their Fruits, and Seeds, and so likewise the Seeds of all Plants may in a manner be called Egges, and Concepti∣ons.

And to this purpose Aristotle speaks, saying: * 1.5 Those creatures which bring forth an Animal from within themselves, have something formed in them up∣on the first conception like unto an egge: for they have an humour conteined in a thin coat, such as that in an egge when the shell is pilled off. Whereupon those de∣pravations of conceptions which fall out about that

time, fluxus vocant, the people call, Fluxes, or mis∣carryings.

Those Fluxes are chiefly observable in Women, when they miscarry in the first or second moneth: and such I have often seen discharged about those times: and such a one also Hippocrates reports to have been discharged, and fallen from the Minstrel.

The first Conception, or Rudiment therefore of all * 1.6 Animals is in the Uterus: which according to A∣ristotle, is liks an egg covered over with a membrane when the shell is pilled off. And this shall appear more clearly by what shall be said hereafter. In the interim we conclude with the Philosopher: All Animals, whether they be swimming, walking, or flying Animals; and whether they be born in the form of an Animal, or of an Egge: are all generated after the same manner.

Notes

• * 1.1

  De form. Ovi & Pulli, c. 1.
• * 1.2

  De gon. an. l. 1. c. 18.
• * 1.3

  Ibid.
• * 1.4

  Hist. an. l. 1. c. 5.
• * 1.5

  De gen. an. l. 3. c. 9.
• * 1.6

  Hist. an. l. 7. c. 7.