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Dividend Two Directory 03
Page 07
The fresh-water mussels and snails and the crayfish burrow deep into the mud and silt at the bottom of ponds and streams where they lie motionless during the winter. The land snails, in late autumn, crawl beneath logs, and, burrowing deep into the soft mould, they withdraw far into their shells. Then each one forms with a mucous secretion two thin transparent membranes, one across the opening of the shell and one a little farther within, thus making the interior of the shell perfectly air-tight. There for five or six months he sleeps, free from the pangs of hunger and the blasts of winter, and when the balmy breezes of spring blow up from the south he breaks down and devours the protecting membrane and goes forth with his home on his back to seek fresh leaves for food and to find for himself a mate.
All those found in the Northern States are perfectly harmless, the true centipede, whose bite is reputed much more venomous than it really is, being found only in the South. True, some of the centipede group can pinch rather sharply with their beetle-like jaws; and one, our largest and most common species, a brownish red fellow about three inches long and without eyes, can even draw blood if its jaws happen to strike a tender place. When handled it always tries to bite, perhaps out of revenge for the abominably long Latin name given it by its describer. In fact the name is longer than the animal itself--_Sco-lo-po-cryp-tops sex-spi-no-sus_ (Say)--being its cognomen in full. With such a handle attached to it, who can blame it for attempting to bite? Yet, to the scientist up on his Latin, each part of the above name bears a definite and tangible meaning. All the myriapods found in the woods and fields feed upon decaying vegetation, such as leaves, stems of weeds, and rotten wood, and in winter three or four species can usually be found within or beneath every decaying log or stump. One species with very long legs, _Scutigera forceps_ (Raf.), is often found in damp houses or in cellars. It is sometimes called the "wall-sweeper," on account of its rapid ungainly gait, and is even reputed to prey upon cockroaches and other household pests.
When a people once homogeneous are separated geographically in such a manner that thorough inter-communication is no longer preserved, all of the agencies by which languages change act separately in the distinct communities and produce different changes therein, and dialects are established. If the separation continues, such dialects become distinct languages in the sense that the people of one community are unable to understand the people of another. But such a development of languages is not differentiation in the sense in which this term is here used, and often used in biology, but is analogous to multiplication as understood in biology. The differentiation of an organ is its development for a special purpose, _i. e._, the organic, specialization is concomitant with functional specialization. When paws are differentiated into hands and feet, with the differentiation of the organs, there is a concomitant differentiation in the functions.
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