I return to the ovary and the upper portion of the fowl's uterus, in which the rudiments of the eggs are produced. These, according to Aristotle,[1] in the first instance are small, and of a white colour; growing larger, they subsequently become of a paler and then of a deeper yellow.
The superior uterus of Fabricius, however, has no existence until after the hen has conceived, and contains the rudiments of ova within it; when it may be designated as a cluster of papulæ. And he therefore observes very properly, "The superior uterus is nothing more than an almost infinite congeries of yelks, which appear collected as it were into a single cluster, of a rounded form, and of every size, from that of a grain of mustard to that almost of a walnut or medlar. This multitude of vitelli is aggregated and conjoined very much in the manner of a bunch of grapes, for which reason I shall constantly speak of it as the vitellarium or raceme of yelks; a comparison which Aristotle himself made in speaking of the soft or scaleless fishes, when he says,[2] their ovary or roe is extruded agglutinated into a kind of raceme or bunch of grapes. And in the same way as in a bunch of grapes the several berries are seen to be of different sizes, some large, some small, some of very diminutive proportions, each hanging by its several peduncle, so do we find precisely the same thing in the vitellarium of the fowl."
In fishes, frogs, Crustacea, and testacea, however, matters are otherwise arranged. The ovary or vitellary here contains ova of one uniform size only, which being extruded increase, attain maturity, and give birth to fœtuses simultaneously. But in the ovary of the common fowl, and almost all the rest of the oviparous tribes, the yelks are found in various stages of their growth, from dimensions that are scarcely visible up to the full size. Nevertheless the eggs of the fowl and other birds, (not otherwise than in those cases where the eggs are all engendered and laid at the same moment,) ripen their fœtuses under the influence of incubation in the same nest, and produce them perfect, nearly at the same time. In the family of the pigeons, however, (which lay and incubate no more than two eggs in the same nest,) I have observed that all the ova crowded together in the ovary, with the exception of a single pair, were of the same
