( Originally Published 1918 )
"WHEN moistening your slices of bread with egg, has it ever occurred to you to examine a little the structure of what furnishes your repast? I think not. Today I am going to tell you something about this : I will show you in detail this wonder called an egg.
"First, let us examine the shell. In hens' eggs it is all white, as also in those of ducks and geese. Turkeys' eggs are speckled with a multitude of little pale red spots. But it is particularly the eggs of undomesticated birds that are remarkable for their coloring. There are sky-blue ones, such as those of certain blackbirds; rose color for certain warblers; and somber green with a tinge of bronze is found, for example, in the eggs of the nightingale. The coloring is sometimes uniform, sometimes enhanced by darker spots, or by a haphazard sprinkling of pigment, or by odd markings resembling some sort of illegible handwriting. Many rapacious birds, chiefly those of the sea, lay eggs with large fawn-colored spots that make them look like the pelt of a leopard. I will not dwell longer on this subject, interesting though it may be, as in telling you the story of the auxiliary birds I have already described the eggs of the principal kinds."
"I have taken care," interposed Jules, "to remember the curious variety of coloring that eggs have. I recall very distinctly the nightingale's, green like an olive ; the goldfinch's, spotted with reddish brown, especially at the larger end; the crow's, bluish green with brown spots; and so many others that I hesitate to say which are my favorites, so nearly equal are they in beauty."
"Let us learn now about the nature of the shell," his uncle continued. "The substance of the shell is, in the hen's egg, as white as marble; its own color not being disguised by any foreign pigment. This pure white and its other characteristics, hardness and clean fracture, do they not tell you of what substance the shell is composed?"
"Either appearances deceive me greatly," answered Louis, "or the shell is simply made of stone."
"Yes, my friend, it is indeed of stone, but stone selected with exquisite care and refined as it were, in the bird's body.
In its nature the eggshell does not differ from common building-stone; or rather, on account of its extreme purity, it does not differ from the chalk that you use on the blackboard, or from the magnificent white marble that the sculptor seeks for the master-pieces of his chisel. Building-stone, marble, and chalk are at bottom the same substance, which is called lime, limestone, or carbonate of lime. The differences, great as they may be, have to do with the state of purity and degree of consistency. That which building-stone contains in a state of impurity from other ingredients is contained also in white marble and chalk, but free from any admixture. Thus in its nature the eggshell is identical with chalk and marble, harder than the first, less hard than the second, being between the two in an intermediate state of pure lime. To clothe the egg, therefore, with a solid envelope, the hen and all birds without exception use the same material as the sculptor works with in his studio and the scholar uses on the blackboard.
"Now, no animal creates matter; none makes its body, with all that comes from it, out of nothing. The bird does not find within itself the material for the eggshell; it gets it from outside with its food. Amid the grain that is thrown to her the hen finds little bits of stone left there through imperfect cleaning; she swallows them without hesitation, knowing full well, however, that they are little stones and not kernels of wheat. That is not enough ; you will see her all day long scratching and pecking here and there in the poultry-yard. Now and then she digs up some worm, her great delicacy, and from time to time some fragment of limestone, which she turns to account with as much satisfaction as if she had found a plump insect."
"I have often seen hens swallowing little stones like that," remarked Emile. ' I thought it was all their own carelessness or gluttonous haste, but now I begin to suspect the truth. Would not those little stones be useful in making the eggshell?"
"You are right, my little friend. The particles of lime swallowed with the food are converted into a fine pap, dissolved by the digestive action of the stomach. By a rigorous sorting the pure lime is separated from the rest, and it is made into a sort of chalk soup which at the right moment oozes around the egg and hardens into a shell. By swallowing little particles of lime, the hen, as you see, lays by materials for her eggshell. If these materials were wanting, if the food given her did not include lime, if, imprisoned in a cage, she could not procure carbonate of lime for herself by pecking in the ground, she would lay eggs without any shell and simply covered with a flabby skin."
"Those soft eggs that hens sometimes lay come then from lack of lime?" asked Louis.
"They either come from the bird's not having had the necessary carbonate of lime in her food or in the earth she pecked, or else her had state of health did not permit the transformation of the little stones into that chalky pap which molds itself around the egg and becomes the shell. In countries where carbonate of lime is scarce in the soil, or even totally lacking, it is the custom to break up the eggshells and mix the coarse powder in the fowl's food. It is a very judicious way of giving the hen in the most convenient form, the stony matter necessary for the perfect formation of the egg."
"Sometimes," observed Louis, "we find on the dunghill eggs of a queer shape and as soft as hens' eggs without the shell. Instead of a chicken, a snake comes out of them. They say they are laid by young cocks."
"You are repeating now one of the false notions prevalent in the country—a foolish notion springing from a basis of actual fact. It is perfectly true that eggs soft, rather long, almost cylindrical, and of the same size at both ends, may be turned up by the fork as it stirs the warm manure of a dunghill. It is also perfectly true that from these eggs snakes are hatched, to the great surprise of the innocent person who thinks he sees there the product of some witchcraft. What is false is the supposed origin of the egg. Never, never has the cock, be he young or old, the faculty reserved exclusively for the hen, the faculty of laying. Those eggs found in dunghills, and remarkable for their strange shape, do not come from fowl; they are simply the eggs of a serpent, of an inoffensive snake which, when opportunity offers, buries its laying in the warm mass of a dunghill to aid the hatching. It is quite natural, then, that from serpents' eggs serpents should hatch."
"The ridiculous marvel of the supposed cock's eggs," returned Louis, "thus becomes a very simple thing; but one must first know. that serpents lay eggs.''
"Henceforth you will know that not only serpents but all reptiles lay eggs just as birds do. Snakes' eggs are flabby, and for covering have only a sort of skin resembling wet parchment. Moreover, they are long in shape, which is far from being the usual form. But the eggs of some reptiles, notably of lizards, have the shell firm and of the fine oval shape peculiar to birds' eggs. If you ever encounter in holes in the wall, or in dry sand well exposed to the sun, little eggs, all white, with shell as fine as a little canary bird's, do not cry out at the strangeness of your discovery; you will simply have come across the eggs of a gray lizard, the usual inhabitant of old walls."