Page:The Works of William Harvey (part 1 of 2).djvu/345

 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