It is a poor substance, indeed, which, when cast aside, is not available for some secondary use in Nature's realm; and the hairs that fall from animals are not all left to return unused to their original elements. The sharp eyes of birds spy them out, and thus the lining to many a nest is furnished. I knew of one feathered seeker of cast-off clothing which met disaster through trying to get a supply at first hand--a sparrow was found dead, tangled in the hairs of a pony's tail. The chickadee often lights on the backs of domestic cattle and plucks out hair with which to line some snug cavity near by for his nest. Before the cattle came his ancestors were undoubtedly in the habit of helping themselves from the deer's stock of "ole clo's," as they have been observed getting their building material from the deer in zoological parks. Of course the hair of deer and similar animals falls out with the motions of the creatures, or is brushed out by bushes and twigs; but we must hope that the shedding place of a porcupine is at a distance from his customary haunts; it would be so uncomfortable to run across a shred of one's old clothes--if one were a porcupine! The skin of birds and animals wears away in small flakes, but when a reptile changes to a new suit of clothes, the old is shed almost entire. A frog after shedding its skin will very often turn round and swallow it, establishing the frog maxim "every frog his own old clothes bag!" Birds, which exhibit so many idiosyncrasies, appear again as utilizers of old clothes; although when a crested flycatcher weaves a long snake-skin into the fabric of its nest, it seems more from the standpoint of a curio collector--as some people delight in old worn brass and blue china! There is another if less artistic theory for this peculiarity of the crested flycatcher. The skin of a snake--a perfect ghost in its completeness--would make a splendid "bogie." We can see that it might, indeed, be useful in such a way, as in frightening marauding crows, who approach with cannibalistic intentions upon eggs or young. Thus the skin would correspond in function to the rows of dummy wooden guns, which make a weak fort appear all but invincible. POLLIWOG PROBLEMS The ancient Phoenicians, Egyptians, Hindus, Japanese, and Greeks all shared the belief that the whole world was hatched from an egg made by the Creator. This idea of development is at least true in the case of every living thing upon the earth to-day; every plant springs from its seed, every animal from its egg. And still another sweeping, all-inclusive statement may be made,--every seed or egg at first consists of but one cell, and by the division of this into many cells, the lichen, violet, tree, worm, crab, butterfly, fish, frog, or other higher creature is formed. A little embryology will give a new impetus to our studies, whether we watch the unfolding leaves of a sunflower, a caterpillar emerging from its egg, or a chick breaking through its shell.