Page:The Works of William Harvey (part 1 of 2).djvu/303

 duty bound, as we readily admit that the office and use of the uterus is the procreation of the egg, so do we maintain the "adequate efficient," as it has been called, the immediate agent to inhere in the egg itself; and we assert farther, that the egg is both engendered and made to increase, not by the uterus, but by a certain natural principle peculiar to itself; and that this principle flows from the whole fowl into the rudiments of the vitellus, and whilst it was yet but a speck, and under the influence either of the calidum innatum or of nature, causes it to be nourished and to grow; just as there is a certain faculty in every particle of the body which secures its nutrition and growth.

As regards the manner in which the yelk is surrounded by the albumen, Aristotle appears to have believed that in the sharp end of the egg (where he placed the commencement of the egg), whilst it was yet surrounded by soft membranes, there existed an umbilical canal, by which it was nourished; a view which Fabricius challenges, denying that there is any such canal, or that the vitellus has any kind of connexion with the uterus. He farther lessens the doubt in regard to the albumen of the extruded egg, observing, that "the egg increases in a two-fold manner, inasmuch as the uterus consists of two portions, one superior, another inferior; and the egg itself consists of two matters the yelk and the white. The yelk increases with a true growth, to wit, by means of the blood, which is sent to it through the veins whilst it is yet connected with the vitellarium. The albumen, however, increases and grows otherwise than the yelk; viz., not by means of the veins, nor by proper nutrition like the yelk, but, by juxtaposition, adhering to the vitellus as it is passing through the second uterus."

But my opinion is, that the egg increases everywhere in the same manner as the yelk does in the cluster; viz. by an inherent concocting principle; with this single difference, that in the ovary the nourishment is brought to it by means of vessels, whilst in the uterus it finds that which it imbibes already prepared for it. Juxtaposition of parts is equally necessary in every kind of nutrition and growth, and so also are concoction and distribution of the applied nutriment. Nor is one of these to be less accounted true nutrition than the other, inas-