ON GENERATION. 263 



The yelk is now contained in the abdomen among the in- 

 testines : and this is the case not merely whilst the chick is in 

 the egg, but even after its exclusion, and when it is running 

 about following its mother in search of food. So that what 

 Aristotle frequently asserts appears to be absolutely true, viz., 

 that the yelk is destined for the food of the chick ; and the 

 chick does certainly use it for food, included in his interior as 

 it is, during the few first days after his exclusion, and until 

 such time as his bill gains the hardness requisite to break and 

 prepare his food, and his stomach the strength necessary to 

 digest it. And, indeed, the yelk of the egg is very analogous 

 to milk. Aristotle gives us his support in this opinion in the 

 place already so frequently referred to r 1 " The chick now lies 

 over much of the yellow, which at last diminishes, and, in pro- 

 cess of time, disappears entirely, being all taken into the body 

 of the bird, where it is stored, so that on the tenth day after the 

 exclusion of the chick, if the belly be laid open, you will still find 

 a little of the yelk upon the intestines." I have myself found 

 certain remains of the yelk even upon the thirteenth day ; and 

 if the argument derivable from the duct of the umbilical veins 

 which we have described as terminating in the porta of the liver 

 by one or another trunk, be of any avail, the chick is already 

 nourished almost in the same manner as it is subsequently, 

 the sustenance being attracted from the yelk by the umbilical 

 vessels, in the same way as chyle is by and by transmitted by 

 the mesenteric veins from the intestines. For the vessels ter- 

 minate in either case in the porta of the liver, to which the 

 nourishment attracted in the same way is in like manner trans- 

 mitted. It is not necessary, therefore, to have recourse to any 

 lacteal vessels of the mesentery, which, in the feathered tribes, 

 are nowhere to be distinguished. 



Let me be permitted here to add what I have frequently 

 found : With a view to discovering more distinctly the relative 

 situations of the embryo and the fluids, I have boiled an egg 

 hard, from the fourteenth day of the incubation up to the day 

 when the exclusion would have taken place, the major part of 

 the albumen being already consumed, and the vitellus divided. 



1 Hist. Anim. lib. vi, cap. 3. 



