Читать книгу Intelligence in Plants and Animals онлайн

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Hardly any animal is more universally distributed than worms. The earth-worm is found in all parts of the world, and some of the genera have an enormous range. They inhabit the most isolated islands, abounding in Iceland, and also being known to exist in the West Indies, St. Helena, Madagascar, New Caledonia and Tahiti. Worms from Kergulen Land in the Antarctic regions have been described by Ray Lankester, and Darwin has reported them as being found in the Falkland Islands. How they reach such isolated islands is quite unknown. They are easily killed by salt water, and it does not seem likely that young worms or their egg-capsules could be carried in earth adhering to the feet or beaks of land-birds, especially to Kergulen Land, for it is not now inhabited by any terrestrial bird.

We have seen that worms are found in nearly every part of the globe, that they are very numerous, as many as 348,480 having been found in an acre of rich ground in New Zealand, and that by the peculiar economy of their nature they are fitted to accomplish a great deal of good in the earth. They have played a more important part in the history of the world than most persons would at first suppose. In many parts of England, according to Darwin, a weight of more than ten tons of dry earth annually passes through their bodies and is brought to the surface in each acre of land, so that the entire superficial bed of vegetable mould passes through their bodies in the course of every few years; and in most parts of the forests and pasture-lands of Southern Brazil, where several species of earth-worms abound, the whole soil to a depth of a quarter of a metre looks as though it had passed through the intestines of worms, even where scarcely any castings are to be observed upon the surface. The upper crust is continually being eaten and ejected by them, thus aiding the fertility of the soil, as well as conveying water and air to the interior by the myriads of burrows which they drill. The vast quantities of leaves that they drag into their holes tend also to enrich the ground. Nor does their good end here. They cover up seeds, undermine rocks, burying them up, and to their labors is due the preservation of many ruins and ancient works of art. Numerous old-time Roman villas have been discovered beneath the ground in England, whose entombments were undoubtedly caused by the worms that undermined them and deposited their castings upon the floors, till finally, aided by other causes, they disappeared from sight.