ON GENERATION. 203 



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 l 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 2 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 vitella- 

 rium. 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 concoc- 

 tion and distribution of the applied nutriment. Nor is one of 

 these to be less accounted true nutrition than the other, inas- 

 1 De General. Animal, lib. iii, cap. 2. * Op cit. p. 11. 



