I have no purpose myself of entering on a general consideration of eggs of all kinds and descriptions; I have not yet given the history of all, but only of the hen’s egg; so that I shall here limit myself to a survey of the uses of the common hen’s egg, keeping in view the end of all its actions, which is nothing less than the production and completion of a new being, as Fabricius has well and truly said.[305]
Among the points having reference to the whole egg, Fabricius speaks of the form, dimensions, and number of eggs. “The figure of the egg is round,” he says,[306] “in order that the mass of the chick may be stowed in the smallest possible space; for the same cause that God made the world round, namely, that it might embrace all things; and it is from this, as Galen conceives, that this figure is always felt to be most agreeable and consonant to nature. Further, as it has no angles exposed to injury from without, it is, therefore, the safest figure, and the one best adapted to effect the exclusion of the chick.” It had been well after such a preface to have assigned satisfactory causes why hen’s eggs are not spherical, like the eggs of fishes, worms and frogs, but oblong and pointed; to have shown what there is in them which hinders the presumed perfection of figure. Now to me the form of the egg has never appeared to have aught to do with the engenderment of the chick, but to be a mere accident; and to this conclusion I come the rather when I see such diversities in the shape of the eggs of different hens. They vary, in short, in conformity with the variety that obtains among the uteri of different fowls, in which, as in moulds, they receive their form.
Aristotle,[307] indeed, says that the longer-shaped eggs produce females, the rounder males. I have not made any experiments upon this point myself. But Pliny[308] asserts, in opposition to Aristotle, that the rounder eggs produce females, the others males. Now were there any certainty in such statements, either in one way or the other, some hens would always produce males, others always females, inasmuch as the eggs of the same hen are in many instances always of one figure, namely, either much rounded or acutely pointed. Horace[309] thought that the oblong eggs, as being the more perfect and better concocted, and therefore the better flavoured, produced males.
I willingly pass by the reasons alleged by Fabricius for the form of eggs, as being all irrelevant.
The size of an egg appears to bear a proportion to the size of the fœtus produced from it; large hens, too, certainly lay large eggs. The crocodile, however, lays eggs the size of those of the goose; nor does any animal attain to larger dimensions from a smaller beginning. It would seem, too, that the size of the egg and the quantity of matter it contained had some connexion with its fecundity, inasmuch as the very small eggs called centenines are all barren.
The number of eggs serves the same end as abundance of conceptions among viviparous animals—they secure the perpetuity of the species. Nature appears to have been particularly careful in providing a numerous offspring to those animals which, by reason of their pusillanimity or bodily weakness, hardly defend themselves against the attacks of others; she has counterbalanced the shortness of their own lives by the number of their progeny. “Nature,” says Pliny,[310] “has made the timid tribes among birds more fruitful than the bold ones.” All generation as it is instituted by nature for the sake of perpetuating species, so does it occur more frequently among those that are shorter-lived and more obnoxious to external injury lest their race should fail. Birds that are of stronger make, that prey upon other creatures, and therefore live more securely and for longer terms scarcely lay more than two eggs once a year. Pigeons, turtle and ring-doves, that lay but a couple of eggs, make up for the smallness of the number by the frequency of laying, for they will produce young as often as ten times in the course of a year. They therefore engender greatly although they do not produce many at a time.
EXERCISE THE SIXTIETH.
Of the uses of the yelk and albumen.
“An egg,” says Fabricius,[311] “properly so called, is composed of many parts, because it is the organ of the engenderer, and Galen everywhere insists on the constitution of an organ as implying multiplicity of parts.” But this view leads us to ask whether every egg must not be heterogeneous, seeing that every egg is organic? And every egg, indeed, even that of the fish and insect, appears to be composed of several different parts,—membranes, coverings, defences; nor is the included matter by any means without diversity of constitution in different parts.
Fabricius agrees farther, and correctly, with Galen, when he says:[312] “Some parts of the egg are the chief instruments of the actions that take place in it, others may be styled necessary,—without them no actions could take place; others exist that the action which takes place may be better performed; others, in fine, are destined for the safety and preservation of all of these.” But he is mistaken when he says: “If we speak of the prime action, which is the generation of the chick, the chief cause of this is the semen and the chalazæ, these two being the prime cause of the generation of the chick, the semen being the efficient cause, the chalaza the matter only.” Now according to the opinion of Aristotle, it must be allowed that that which generates is included in the egg; but Fabricius denies that the semen of the cock is contained in the egg.