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Page:Popular Science Monthly Volume 24.djvu/500

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THE POPULAR SCIENCE MONTHLY.

DEFENSES OF THE LESSER ANIMALS.
By Professor L. GLASER.

ALL organic beings are, in the course of their lives, subject to a series of dangers and destructive influences arising from the conditions of climate and temperature, and from the competition of their fellow-beings, the universality and power of which are well illustrated in Darwin's phrase, "the struggle for existence." Yet all creatures are adjusted with most wonderful art and adaptation to the conditions of their existence and the state of the world around them. Among these adaptations are the means given to the most helpless animal existences for securing themselves against the depredations of their enemies. It is proper to observe, in considering this subject, that the protection enjoyed by the lower animal organisms is not absolute and individual, but that it is generally effective principally for the preservation of the species against destruction. For where peculiar means of protection are given to one creature, corresponding means for overcoming it are often given to another, its enemy. To the protective sharp sight of the rodents and birds are opposed the equally sharp sight of the fox and the long range of vision of the hawk. It is only in averaging the mass of such animals that we find they are secured as a whole against danger, while numerous individuals are overtaken by their enemies.

Some of the higher animals illustrate the manner in which Nature contrives to furnish special measures of precaution for its little-gifted, unalert, unarmed, and helpless creatures. The absence of teeth in the edentates is offset by shields or scale-armor; helpless beetles are furnished with hard wing-cases; the pheasants, quails, and larks of the fields are hidden from the keen vision of birds of prey by their earthy color, birds of the river and sea-shore by their resemblance in color to the sand and shingle.

Protection is required by the lower animals chiefly against the weather and against parasites and other external enemies. Frequently the place of their abode is their only and ordinarily a sufficient protection, as is the case with earth-worms and burrowing larvæ, wood-worms and fruit-borers. But such animals appear to be afflicted with particular enemies peculiarly fitted to hunt them out in their otherwise secure fortresses—in the shape of moles, mole-crickets, long-nosed hedgehogs, shrew-mice, and swine, hook-billed lapwings, and sharp-tongued woodpeckers. Frequently, also, each animal is defended by some special relation peculiar to its species. Insects, which in their comparatively brief state of maturity are secured by their powers of flight, have to be guarded, in their three previous conditions of egg larva, and pupa, against hosts of enemies to which they would other-