Page:Popular Science Monthly Volume 28.djvu/348

336 enough to explain by the fashionable clew of "adaptation to environment." Ponds arc always very likely to dry up, and so the animals that frequent ponds are usually capable of bearing a very long deprivation of water. Indeed, our evolutionists generally hold that land animals have in every case sprung from pond-animals which have gradually adapted themselves to do without water altogether. Life, according to this theory, began in the ocean, spread up the estuaries into the greater rivers, thence extended to the brooks and lakes, and finally migrated to the ponds, puddles, swamps, and marshes, whence it took at last, by tentative degrees, to the solid shore, the plains, and the mountains. Certainly the tenacity of life shown by pond-animals is very remarkable. Our own English carp bury themselves deeply in the mud in winter, and there remain in a dormant condition many months entirely without food. During this long hibernating period, they can be preserved alive for a considerable time out of water, especially if their gills are, from time to time, slightly moistened. They may then be sent to any address by parcels-post, packed in wet moss, without serious damage to their constitution; though, according to Dr. Günther, these dissipated products of civilization prefer to have a piece of bread steeped in brandy put into their mouths to sustain them beforehand. In Holland, where the carp are not so sophisticated, they are often kept the whole winter through, hung up in a net to keep them from freezing. At first they require to be slightly wetted from time to time, just to acclimatize them gradually to so dry an existence; but after a while they adapt themselves cheerfully to their altered circumstances, and feed on an occasional frugal meal of bread and milk with Christian resignation.

Of all land-frequenting fish, however, by far the most famous is the so-called climbing-perch of India, which not only walks bodily out of the water, but even climbs trees by means of special spines, near the head and tail, so arranged as to stick into the bark and enable it to wriggle its way up awkwardly, something after the same fashion as the "looping" of caterpillars. The tree-climber is a small, scaly fish, seldom more than seven inches long; but it has developed a special breathing apparatus to enable it to keep up the stock of oxygen on its terrestrial excursions, which may be regarded as to some extent the exact converse of the means employed by divers to supply themselves with air under water. Just above the gills, which form of course its natural hereditary breathing apparatus, the climbing-perch has invented a new and wholly original water-chamber, containing within it a frilled bony organ, which enables it to extract oxygen from the stored-up water during the course of its aerial peregrinations. While on shore it picks up small insects, worms, and grubs; but it also has vegetarian tastes of its own, and does not despise fruits and berries. The Indian jugglers tame the climbing-perches and carry them about with them as part of their stock in trade; their ability to