Page:The Works of William Harvey (part 1 of 2).djvu/323

Rh me, nevertheless, this does not appear likely; because it is certain that the whole ovary being removed, the uterus secundus also diminishes in size in the same proportion, and shrinks into a mere membrane, which contains neither any fluid nor any albumen. Fabricius proceeds: "The ova centenina are met with of two kinds: one of them being without a yelk, and this is the true centenine egg, because it is the last which the hen will lay at that particular season she will now cease from laying for a time. The other is also a small egg, but it has a yelk, and will not prove the last which the hen will then lay, but is intermediate between those of the usual size that have preceded, and others that will follow. It is of small size because there has been a failure of the vegetative function, as happens to the peach, and other fruit, of which we see many of adequate size, but a few that are very diminutive." This may be in consequence of the inclemency of the weather, or the want of sun, or from defective nutriment in point either of quantity or quality. I should not readily allow, however, that the eggs last laid are always small.

Monstrous eggs are not wanting; "for the augurs," says Aristotle, "held it portentous when eggs were laid that were all yellow; or when, on a fowl being laid open, eggs were found under the septum transversum, where the rudimentary eggs of the female usually appear, of the magnitude of perfect eggs.

To this head may be referred those eggs that produce twins, that have two yelks. Such an egg I lately found in the uterus of a fowl, perfect in all respects, and covered with a shell; the yelks, cicatriculæ, and thicker albuminous portions being all double, and the chalazæ present in two pairs: a single thinner albumen, however, surrounded all these, and this in its turn was included within the usual double common membrane, and single shell. For, indeed, although Aristotle says that fowls always lay some eggs of this kind, I shall hardly be induced to believe that this does not occur against the ordinary course of nature. And although twin chicks are produced from such eggs as I have ascertained in opposition to the opinion of Fabricius, who says that they produce chicks having four legs, or four wings and two heads, which, however, are not