Eggshell

“ He does not eat the eggs. All that is inside he takes out, and only does he keep the shell. Eggshell is not good to eat. Nor does he eat the eggshells, but puts them away in soft boxes where they will not break. He catch many small birds. ”

“ Particles of sharp rock from the nest cavity may adhere to the shell, and result in rupturing, perhaps at weak spots where prolonged contact with the soil has caused deterioration. The female tends to keep her eggs in a compact cluster, shifting their position frequently so that no part of an eggshell adheres to its surroundings long enough for rotting to occur, and most of the surface of each egg is exposed to the air.
Another important function of the brooding female seems to be that of altering the nest burrow and shifting the eggs so that the effects of unfavorable weather are minimized. ”

“ Hens pick out the grains of Oats from Horse-dung, which are full of salt, preferring them to fresh Oats, and thence become more fruitful, in laying more Eggs, the salt concocting the small stones which they swallow, in their Ventricles, is the first matter of Eggshells; but if, being shut up in Pens or Coops, they have not that salt earth, with the small sand or stones, which they usually devour, or their stomachs being weak, doth not digest them, the Eggs they lay afterwards, will be such as we call windy Eggs, having no shells, or such as are very imperfect. ”

“ I dare say you find it hard to believe. I did, with the thing before me. There the egg had been, sunk in that cold black mud, perhaps three hundred years. But there was no mistaking it. There was the—what is it?—embryo, with its big head and curved back, and its heart beating under its throat, and the yolk shrivelled up and great membranes spreading inside of the shell and all over the yolk. Here was I hatching out the eggs of the biggest of all extinct birds, in a little canoe in the midst of the Indian Ocean. ”

“ Within a few hours after, the female, thus impregnated, begins to lay her eggs in the following manner. She singles out a leaf, grass, or some such matter, that is floating just below the surface of the water, in some pond, and, hovering in the air about a foot above this spot, on a sudden she descends, and dips the extremity of her tail in the water, at which instant she discharges an egg, that at the moment of its emission is inveloped in a glutinous liquid, sufficiently tenacious to enable it to adhere firmly on the floating substance above-mentioned without sinking. ”

“ Each is no bigger than a tiny pin’s head. Instead of having shells, however, these eggs have tough but very elastic skins; and these skins are made in such a way that while they allow water to soak in from the outside, they will not allow it to pass out again. So as soon as the eggs are dropped into the sea they begin to swell; and the result is that before very long each egg is as big as a good-sized pea.
If you pick up a cluster of these curious eggs in the early spring and open them, you will find inside each the shell of a very tiny whelk, which is almost ready to hatch out. ”

“ The adults rarely pay any attention to the eggs, which are hatched directly by the heat of the sun or by heat absorbed from the water. The length of incubation varies much. When the young fish leaves the egg-shell it carries, in the case of most species, a part of the yolk still hanging to its body. Its eyes are very large, and its fins are represented by thin strips of membrane. It usually undergoes no great changes in development from the first, resembling the adult except in size. ”

“ CHEMISTRY OF A HEN'S EGG.
Before proceeding to inquire into the interior composition of the egg, we will consider the exterior covering, or the shell—the physical and chemical structure of which is exceedingly interesting and wonderful. The white, fragile cortex called the shell, composed of mineral matter, is not the tight, compact covering which it appears to be; for it is everywhere perforated with a multitude of holes too small to be discerned by the naked eye, but which, with the aid of a microscope, are distinctly revealed. ”

“ I have even known the eggs carelessly dropped on the bare ground in a corner of a potato-field, and have found the female sitting on her eggs in all the bright glare of a noonday sun in June, and to all appearance undisturbed by its brilliance. A more common situation for the eggs is a slight hollow of a bare rock, the dark weather-beaten shades of which, with its brown and slate-colored mosses and lichens, resembling both the parent and the egg in their coloring, are well adapted to screen them from observation or detection. ”

“ Should all the conditions be satisfactory, the egg soon begins to show signs of life. It is left to nature to hatch, and the time occupied in the process varies greatly. If an egg-case be opened after some time, a tiny embryo worm, or sometimes a pair, will be found inside, surrounded by a glutinous fluid. The young worm as it grows expands its case, and ultimately emerges—not as a caterpillar or larva, for it goes through no metamorphoses as does the butterfly or frog, the sawfly or even the fish, but as a worm; and now it has only to hasten development and become adult. ”

“ The white of the egg consists of two parts, each of which is enveloped in distinct membranes. The outer bag of albumen, next the shell, is quite a thin, watery body, while the next, which invests the yolk, is heavy and thick. But few housekeepers who break eggs ever distinguish between the two whites, or know of their existence even. Each has its appropriate office to fulfill during the process of incubation or hatching, and one acts, in the mysterious process, as important a part as the other. ”

“ Some change their shape so much that, as they age, they have to dissolve all the partitions made in their youth in the shell. The eggs of some are scattered on the surface of the water, while the eggs of others are hatched by the mother before being turned adrift. ”

“ Finally, there are insects in whose egg-tubes the egg-compartments are arranged in a single row, while the capacious terminal chamber contains a large mass of food-cells.
Egg-cells, nutritive cells, as well as the cells of the follicle epithelium (epithelium of the chambers of the ovarian tubes) , originate as similar or homologous elements, division of labor leading to their later differentiation. Only a few of the numerous egg-germs develop into eggs, the rest serving as envelopes and also as food for these few. ”

“ The skin you saw on the bean serves for the shell. There is an inner skin often, like the silken skin inside the egg-shell. The food stored up in the seed-leaves serves as the yolk and white of the egg. The tiny germ between answers to the spot in the yolk, which is the chick germ.
The seeds of flowers differ more than the eggs of birds and insects. For some seeds have no coats at all. Some have only one. ”

“ At the moment of hatching, the shell breaks, or rather opens like a hinged box-cover. A large number of the eggs look like seeds. Some are round, others cylindrical, conical, or hemispherical. Others represent solid forms, either flattened or terminating in a point. A curious study is furnished by the art with which the females deposit their eggs. Here we find single eggs; there we see them collected in considerable numbers within a parchment or silken protective envelope, which floats on the water, or is inserted in bark or attached to a stone. ”

“ Not only so, but it is known that the eggs of some other insects are laid in the egg of the green-fly, and in one instance it has been found that yet another insect laid its egg in the egg of the parasite!
Some of the most interesting objects in nature are the buds in which, all neatly packed and stowed away, the young leaves and flowers remain awaiting the warm breath of spring. They are most interesting to examine: one finds series after series of overlapping scales which cover one another in the most ingenious way. ”

“ As a rule, the colour of the egg turns darker as the time for the arrival of the infant larva approaches, and you will often be able to see a little brown or black head moving slightly within the 'shell.' You may know then that the hatching is close at hand, and the movements of the tiny creature are well worth careful watching. ”

“ The eggs, which are generally laid singly or in pairs on either side of a leaf, sometimes on a stalk, are yellowish-green in colour. The shell is said to be netted, but under a fairly strong lens this does not show. About four hundred is probably the average number for a female to lay in a state of nature, but they seem not to deposit so many when reared from the egg in confinement. ”

“ The yolk therefore is not necessary to the spawn of fish, the eggs of insects, or for the seeds of vegetables; as their embryons have probably their food presented to them as soon as they are excluded from their shells, or have extended their roots. Whence it happens that some insects produce a living progeny in the spring and summer, and eggs in the autumn; and some vegetables have living roots or buds produced in the place of seeds, as the polygonum viviparum, and magical onions. ”

“ The food of this species principally consists of insects; but we have frequently found in its stomach substances of a vegetable nature also, as pulpy berries, and seeds of various kinds. Its eggs, which are about half-an-inch in length, irregularly oval and flattened, are laid in any crevice; they are covered with a hard and brittle calcareous shell. The young, when excluded, are exactly like the adult, but have the hues much more brilliant: they are able to run with agility the moment they leave the shell. ”

“ It is true that we are not acquainted with any eggs endowed with such properties. I have already considered this subject in the ninth chapter of my Dissertation. I there show how several kinds of eggs of insects—not to speak of eggs of birds—perish under a heat less than that of boiling water. I have shown also that the seeds of plants are destroyed when they are exposed to the heat of boiling water, and that even those whose outer coat is of the hardest description are not thereby spared. ”

“ The analogy between seeds and eggs has long been observed, and is confirmed by the mode of their production. The egg is known to be formed within the hen long before its impregnation; C.F. Wolf asserts that the yolk of the egg is nourished by the vessels of the mother, and that it has from those its arterial and venous branches, but that after impregnation these vessels gradually become impervious and obliterated, and that new ones are produced from the fetus and dispersed into the yolk. ”

“ For the Horse's skull our people have substituted an egg-shell on the top of a switch stuck among the cabbages. It is easier to arrange; also it is quite as useful, that is to say, it has no effect whatever.
Everything, even the nonsensical, is capable of explanation with a little credulity. When I question the peasants, our neighbours, they tell me that the effect of the egg-shell is as simple as can be: the Butterflies, attracted by the whiteness, come and lay their eggs upon it. Broiled by the sun and lacking all nourishment on that thankless support, the little caterpillars die ”

“ If then the eggs are blown, or carried by some means to water they will continue their development, on dry soil they cannot long survive. Each egg gives rise to a little organism which swims freely in the water; it is shaded like a blunt-ended cone when extended and is roughly oval when contracted. Its body is covered with little whip-like structures similar to those of the slipper animalculæ, and it is due to the lashing of these little whips that the creature moves through the water. ”

“ When the egg is ripe the food-chamber disappears because its contents have served for the formation of the egg below it. In Lepidoptera especially, the egg-tubes resemble strings of pearls because most of the numerous eggs ripen simultaneously and are likewise deposited at the same period, which is naturally not the case in those insects whose eggs gradually ripen (Fig. 477) . In other cases the egg- or food-compartments are transformed into each other, but only one egg- and one food-compartment can be situated in the same dilatation of the ovarian tube. ”

“ We usually think of eggs as consisting of a yolk surrounded by albumen, and enclosed in a hard shell made of lime or some form of calcium. The eggs of birds and fowls are our types, but the egg of the Earthworm has no chalk-like shell. ”

“ The external covering of the egg, called by Pliny the cortex and putamen, by Quintus Serenus the testa ovi, is a hard but thin, friable and porous covering, of different colours in different cases—white, light green, speckled, &c. All eggs are not furnished with a shell on their extrusion: the eggs of serpents have none; and some fowls occasionally, though rarely, lay eggs that are without shells. ”

“ The egg left to itself decays like other organized substances, but with our assistance in simply transferring it to a place where the temperature is in a certain uniform condition, in a few weeks, the albumen, water, oil and mineral salts are transferred into a living chick, which thrusts its little beak through the shell, and in ten minutes is running about, almost able to take care of itself. ”

“ Some morning, on going to his troughs, he will notice broken egg-shells in the water, and, on closer inspection, will observe wriggling nondescripts on the bottom, neither like fish nor eggs, but compounded of both. When they once begin to appear, they come in thousands, in millions, in myriads. The young need more water, at this time, but require less care ”

“ That the eggs laid by birds should offer to some extent characters of utility to systematists is only to be expected, when it is considered that those from the same nest generally bear an extraordinary family likeness to one another, and also that in certain groups the essential peculiarities of the egg-shell are constantly and distinctively characteristic. ”