What a vast difference is there between the bright-winged insect, whose history we traced in our volume on Butterflies, and the bird with downy plumage and the voice of melody; between that again and the great crocodile, in his scaly coat of mail; the mighty boa constrictor, king of serpents; or that tyrant of the deep, the fierce voracious shark; and yet all these come from Eggs, very similar in form, and precisely so in their nature and internal construction. Look too at the difference in size, between the egg of the Humming Bird, no bigger than a pea, and that of the Ostrich, as large as a man's head nearly, or bigger still that of the Epyornis, of which fossil remains have been found in Madagascar, the contents of which must have been equal to six ostrichs', or one hundred and forty-eight common hens' eggs, that is about seventeen English pints; and yet in all these the germ, or as it would be called, the vital principle, that is, the principle of life, is but a tiny speck, or circle, which is attached to the membrane that surrounds the yellow portion, or yolk; it is from this that the animal in embryo derives nourishment, and the size of it, and consequently of the whole egg, is in proportion to the quantity that is required to sustain life, until the protection of the shell is no longer necessary. There is only so much food stored up as the bird, or reptile, or whatever it may be, requires before it is strong enough to make an opening in its prison, and come forth to provide for itself, or be fed by the parent. Some creatures that eventually attain a large size are born, or _hatched_, as it is termed, comparatively small; thus the size of the egg is not always in proportion to that of the animal which lays it; the crocodile's egg, for instance, is but little larger than that of the common fowl; the young comes forth like a small lizard, about two or three inches long, takes to the water at once, and begins to catch insects on its own account; its mother may be twenty or thirty feet in length. Most creatures that produce eggs small in proportion to their size lay a great many; this is especially the case with fish, whose _spawn_ must be numbered by millions: it has been calculated that if the young of a single pair of herrings were suffered to breed undisturbed, they would in twenty years together make up a bulk six times the size of the earth; but so many creatures feed upon this spawn, that few of the eggs of which it is composed ever come to young fish, that is comparatively few, for the vast shoals which every year visit our shores, for the purpose of depositing their spawn in shallow water, shew that immense numbers must escape the dangers to which they are exposed. There are some fish of the fierce and rapacious kind, such as the Ray, the Dog-fish, and the Shark, which attain a considerable size before they lose the protection of the egg-shell, which is of a very peculiar shape and construction, being of a leathery texture,