Our author states that, in 1796, a terrible inundation was produced in the Indalself, which rises in the Storsjo in Jemtland, by drawing off into it the waters of another lake near Ragunda. The flood destroyed houses and fields; much earth was swept into the channel, and the water made turbid and muddy; the salmon and the smaller fish forsook the river altogether, and never returned. The banks of the river have never regained their former solidity, and portions of their soil are still continually falling into the water and destroying its purity.--Resa genom Sverge, ii, p. 61.] Industrial operations are not less destructive to fish which live or spawn in fresh water. Mill-dams impede their migrations, if they do not absolutely prevent them, the sawdust from lumber mills clogs their gills, and the thousand deleterious mineral substances, discharged into rivers from metallurgical, chemical, and manufacturing establishments, poison them by shoals. [Footnote: The mineral water discharged from a colliery on the river Doon in Scotland discolored the stones in the bed of the river, and killed the fish for twenty miles below. The fish of the streams in which hemp is macerated in Italy are often poisoned by the juices thus extracted from the plant.-Dorotea, Sommario della storia dell' Alieutica, pp. 64, 65.] We have little evidence that any fish employed as human food has naturally multiplied in modern times, while all the more valuable tribes have been immensely reduced in numbers. This reduction must have affected the more voracious species not used as food by man, and accordingly the shark, and other fish of similar habits, even when not objects of systematic pursuit, are now comparatively rare in many waters where they formerly abounded. The result is, that man has greatly reduced thenumbers of all larger marine animals, and consequently indirectly favored the multiplication of the smaller aquatic organisms which entered into their nutriment. This change in the relations of the organic and inorganic matter of the sea must have excercised an influence on the latter. What that influence has been we cannot say, still less can we predict what it will be hereafter; but its action is not for that reason the less certain. [Footnote: Among the unexpected results of human action, the destruction or multiplication of fish, as well as of other animals, is a not unfrequent occurrence. Footnote: Williams, in his History of Vermont, i., p. 140, records such a case of the increase of trout. In a pond formed by damming a small stream to obtain water power for a sawmill, and covering one thousand acres of primitive forest, the increased supply of food brought within reach of the fish multiplied them to that degree, that, at the head of the pond, where, in the spring, they crowded together in the brook which supplied it, they were taken by the hands at pleasure, and swine caught them without difficulty. A single sweep of a small scoopnet would bring up half a