Why do birds exceed quadrupeds in the quantity of their respiration?
Because the birds may more effectually perforate the shell, and thus contribute to their own liberation. This sharp prominence or appendage, becomes opposed to the shell at various points, in a line extending throughout its whole circumference, about one-third below the larger end of the egg; and a series of perforations, more or less numerous, is thus effected by the increasing strength of the bird, weakening the shell in a direction opposed to the muscular power of the little captive, which is thus ultimately enabled, by its own efforts, to break the walls of its prison. In the common fowl, this horny appendage falls off in a day or two after the chick is hatched; in the pigeon, it sometimes remains on the beak ten or twelve days : thus arises, doubtless, from the young pigeons being fed by the parent bird some time after being hatched; and thus there is no occasion for the young using its beak to pick up food. This singular fact was first noticed by Mr. Yarrel, a clever contributor
