Page:The Works of William Harvey (part 1 of 2).djvu/378

 must infallibly conclude that the egg, even when contained in the ovary, does not live by the vital principle of the mother, but is, like the youth who comes of age, made independent even from its first appearance; as the acorn taken from the oak, and the seeds of plants in general, are no longer to be considered parts of the tree or herb that has supported them, but things made in their own right, and which already enjoy life in virtue of a proper and inherent vegetative power.

But if we now admit that there is a living principle in a fertile egg, it may become matter of discussion whether it is the same living principle which already inheres in the egg that will in- here in the future chick, or whether it is a different one that actuates each ? For it is matter of necessity that we admit the inherence of a certain principle which constitutes and causes the egg to grow, and which farther engenders and makes the chick to increase. We have to inquire, therefore, whether the animating principle of the egg and of the chick be one and the same, or several and different ? And then, were several vital principles recognized, some appertaining to the egg, others to the chick, we should next have to inquire : whence and at what epoch the animating principle of the chick entered it? and what is it in the egg which causes the cicatricula to dilate before the advent of the living principle; which draws the eye of the vitellus upwards, as stated, and produces the colliquament, changes the constitution of the fluids of the egg, and preordains everything for the construction of the future chick before there is even a vestige of it to be seen? Or whence shall we say the aliment fit for the embryo is derived, and by which it is nourished and made to grow, before it is yet in being ? For these acts are seen to be the work of the vegetative soul of the embryo, and have reference to the coming pullet, ensuring its nutrition and growth. And again, when the embryo is begun, or the chick is half formed, what is it which constitutes that embryo or that chick one and continuous and connex with the liquids of the egg ? What nourishes and makes the chick to grow, and pre- serves the fluids that are fit for its nutrition from putrefaction, and prepares, and liquefies, and concocts them ?

If the vital principle be the act of the organic body possessing life inpotentia, it seems incredible that this principle can inhere in the chick before something in the shape of an organized body