of the foetal chick's existence a more delicate food is prepared for it ; more advanced, firmer and firmer food is supplied ; and this is the reason, I apprehend, wherefore, the perfect egg con- sists not only of two portions of different colours, but is even provided with two kinds of albumen.
Now all this that we discover from actual experience of the matter accords with the opinion of Aristotle, where he says r 1 " The part which is hot is best adapted to give form to the limbs ; that which is more earthy rather conduces to the con- stitution of the body and is more remote. Wherefore in eggs of two colours, the animal begins to be engendered from the white (for the beginning of animal life is in the hot), and derives its nourishment from the yellow. In the warmer animals, con- sequently, these parts are kept distinct from one another, viz. that from which the beginning is derived, and that whence the nourishment is obtained, and the one is white, the other yellow."
From what has now been said it appears that the chick and we shall show that it is not otherwise in all other animals arises and is constituted as it were by a principle or soul inherent in the egg, and that in the same way the proper ali- ment is sought for and is supplied within the egg ; whereby it comes that the chick is not dependent on its mother in the same way as plants are dependent on the ground ; and it is not more correct to say that the chick is nourished by the blood of its mother, or that its heart beats, and that it lives through the spirits of its parent, than it would be to assert that it moved and felt through the organs, or grew and attained to adult age through the vital principle of its parent. It is mani- fest, on the contrary, and is allowed by all that the foetal chick is nourished through its umbilical vessels; and that the vascular ramifications dispersed over the albumen and yelk imbibe nou- rishment from them and convey it to the foetus. It is also ad- mitted that the chick, when excluded from the shell, is supplied with nourishment, partly from yelk, partly from chyle, and that in either case the aliment passes by the same route, viz. by the vena portse into the liver, the branches of this vessel effecting the transit.
It is therefore obvious, as I now say by the way, that the
1 De Gen, Anim. lib. iii, cap. 1.
