258 ON GENERATION. 



superior, another inferior ; but the albumen in the middle is 

 liquid, and still extends under the inferior portion of the vitellus, 

 as it did previously." Thus far Aristotle. 



And now the arteries are seen distinctly accompanying the 

 veins, both those that proceed to the albumen and those that 

 are distributed to the vitellus. The vitellus also at this time 

 liquefies still more and becomes more diffluent, not entirely, in- 

 deed, but, as already said, that portion of it which is uppermost ; 

 neither do the branches of the veins proceed to every part of 

 the vitellus alike, but only to that part which we have spoken 

 of as resembling melted wax. The veins that are distributed to 

 the albumen have, in like manner, arteries accompanying 

 them. The larger portion of the albumen now dissolves into a 

 clear fluid, the colliquament, which surrounds the embryo that 

 swims in its middle, and comes between the two portions of 

 the vitellus, viz., the superior and the inferior; underneath 

 all (in the sharp end of the egg), the thicker and more viscid 

 portion of the albumen is contained. The superior portion of 

 the yelk already appears more liquid and diffluent than the in- 

 ferior; and wherever the branches of the veins extend, there the 

 matter seems suddenly to swell and become more diffluent. 



" On the tenth day," continues our author, " the albumen 

 subsides, having now become a small tenacious, viscid, and 

 yellowish mass" so much of it, that is to say, as has not passed 

 into the state of colliquament. 



For already the larger portion of the white has become 

 dissolved, and has even passed into the body of the embryo, 

 viz., the whole of the thinner albumen, and the greater portion 

 of the thicker. The yelk, on the contrary, rather looks larger 

 than it did in the beginning. Whence it clearly appears that 

 the yelk has not as yet served for the nutrition of the embryo, 

 but is reserved to perform this office by and by. In so far as 

 we can conjecture from the course and distribution of the veins, 

 the embryo from the commencement is nourished by the colli- 

 quament ; upon this blood-vessels are first distributed, and then 

 they spread over the membrane of the thinner albumen, next 

 over the thicker albumen, and finally over the vitellus. The 

 thicker albumen serves for nutriment after the thinner; the 

 vitellus is drawn upon last of all. 



