heart, is no longer seen to move externally, but to be covered over and concealed; still its two meatus venosi are perceived more distinctly than before, one of them being, further, larger than the other. " But our learned author was mistaken here; for this familiar divinity, the heart, enters into his mansion and shuts himself up in its inmost recesses a long time afterwards, and when the house is almost completely built. Aldrovandus also errs when he says, " by the vis insita of the veins, the remaining portion of the albumen acquires a straw colour," for this colour is ob- served in the thicker albumen of every spoilt egg, and it goes on increasing in depth from day to day as the egg grows staler, and this without any influence of the veins, the thinner portion only being dissipated.
But the embryo enlarging, as we say below, and the ramifi- cations of the meatus venosi extending far and wide to the al- bumen and vitellus, portions of both of these fluids become liquefied, not indeed in the way Aldrovandus will have it, from some vis insita in the vessels, but from the heat of the blood which they contain. For into whatsoever part of either fluid the vessels in question extend, straightway liquefaction ap- pears in their vicinity; and it is on this account that the yelk about this epoch appears double : its superior portion, which is in juxtaposition with the blunt end of the egg, has already become more diffluent than the rest, and appears like melted yellow wax in contrast with the other colder firmer por- tion; like bodies in general in a state of fusion, it also occupies a larger space. Now this superior portion, liquefied by the genial heat, is separated from the other liquids of the egg, but particularly the albumen, by a tunica propria of extreme tenuity. It therefore happens that if this most delicate, fragile, and in- visible membrane be torn, immediately there ensues an admix- ture and confusion of the albumen and vitellus, by which every- thing is obscured. And such an accident is a frequent cause of failure in the reproductive power, (for the different fluids in question are possessed of opposite natures,) according to Aristotle, 1 in the place already so frequently referred to : " Eggs are spoiled and become addled in warm weather especially, and with good reason; for as wine grows sour in hot weather, the lees
1 De Gener. Anim. lib. iii, c. 2.
