Elementary biology; an introduction to Elementary biology; an introduction to the science of life elementarybiolog00grue Year: 1924 PROTECTIVE ACTIVITIES 371 ocean and a constant current of water brings oxygen and food, and carries off wastes and reproductive cells (see Fig. 44). When we come to the highest animals (the insects) of the branch arthropods and the highest animals of the backboned branch (birds and mammals), we find very complex activities related to the making of homes. The solitary wasp goes no farther than burying a few insects that later serve as food for the young. The socia
Elementary biology; an introduction to Elementary biology; an introduction to the science of life elementarybiolog00grue Year: 1924 PROTECTIVE ACTIVITIES 371 ocean and a constant current of water brings oxygen and food, and carries off wastes and reproductive cells (see Fig. 44). When we come to the highest animals (the insects) of the branch arthropods and the highest animals of the backboned branch (birds and mammals), we find very complex activities related to the making of homes. The solitary wasp goes no farther than burying a few insects that later serve as food for the young. The social wasps and hor- nets, like the related bees and ants, build very elaborate homes out of 'paper' (which they make from wood pulp and other materials) and out of wax and earth (see Fig. 187). Nest-building among the birds involves complex instincts, and pos- sibly in some cases a degree of real intelligence. From the crude whisps of the grouse, or the simple mud heap of the flamingo, to the deli- cate and skillful work of the tailor bird, we find a long series of nests of many degrees of complexity in structure. But with the exception Fig. 190. Nettling cell of jellyfish This specialized skin cell, A, con- tains a fine coiled thread suspended in a capsule of acid fluid, ^^'hen the surface is disturbed at the trigger, /, the coil suddenly straightens out, shooting the sharp needle into the surrounding space, and at the same time the acid fluid from the cell passes through the hair. The sting- ing sensation is probably produced by this fluid. B, the discharged cell of homes made in hollows, like that of the woodpecker, whatever shelter nests may furnish serves almost exclusively for the protection of the young (Fig, 188). Indeed, we may say that the making of shelter among the higher animals is closely related to the protection of the young,
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