ON GENERATION. 245 



rudiment of the head, which first becomes visible on the fifth 

 day, very soon after which the eyes are distinguishable, being 

 from the first of large size and prominent, and marked off from 

 the rest of the head and body by a certain circumfusion of black 

 matter. Either of the eyes is larger than the whole of the rest 

 of the head, in the same way as the head surpasses the remainder 

 of the body in dimensions. The whiteness of the body, and 

 prominence of the eyes, (which, as well as the brain, are filled 

 internally with perfectly pellucid water, but externally are of 

 a dark colour), continue for some time up to the tenth day, 

 and even longer; for, as we have seen, Aristotle says that " the 

 eyes decrease at a late period, and contract to the proper pro- 

 portion." But for my own part, I do not think that the eyes 

 of birds ever contract in the same ratio which we observe be- 

 tween the head and eyes of a viviparous animal. For if you 

 strip off the integuments from the head and eyes of a fowl or an- 

 other bird, you will perceive one of the eyes to equal the en- 

 tire brain in dimensions; in the woodcock and others, one of 

 the eyes indeed is as large as the whole head, if you make ab- 

 straction of the bill. But this is common to all birds that the 

 orbit or cavity which surrounds the eye is larger than the brain, 

 a fact that is apparent in the cranium of every bird. Their 

 eyes, however, are made to look smaller, because every part, 

 except the pupil, is covered with skin and feathers ; neither are 

 they possessed of such a globular form as would cause them to 

 project ; they are of a flatter configuration, as in fishes. 



" In the lower part of the body," says the philosopher, " we 

 perceive the rudiments of no member corresponding with the 

 superior members." And the thing is so in fact; for as the body 

 at first appears to consist of little but head and eyes, so inferiorly 

 there is neither any extremity, wings, legs, sternum, rump, 

 nor any viscus apparent; the body indeed is still without any kind 

 of proper form; in so far as I am able to perceive, it consists 

 of a small mass adjacent to the vein, like the bent keel of a 

 boat, like a maggot or an ant, without a vestige of ribs, wings, 

 or feet, to which a globular and much more conspicuous mass is 

 appended, the rudiment of the head, to wit, divided, as it seems, 

 into three vesicles when regarded from either side, but in fact 

 consisting of four cells, two of which, of great size and a black 

 colour, are the rudiments of the eyes ; of the remaining two 



