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Page:Popular Science Monthly Volume 19.djvu/582

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566
THE POPULAR SCIENCE MONTHLY.

tance of between six and eight hundred miles. At these distances the bodies of the fish become covered with bruises, in which patches of white fungus are developed; their fins become mutilated, their eyes are often destroyed, parasitic worms gather in their gills, they become emaciated, the flesh becomes white from the loss of the oil, and they all die as soon as the spawning act is accomplished, often before. So far as has been observed, they are not known to feed after entering the rivers. The spawning-season varies in different rivers, and different parts of the same river, but not in the different species, and probably extends from July to December. In the spring the fish are silvery, spotted or not, according to the species, and have the mouth about equally symmetrical in both sexes. As the spawning-season approaches, the female loses her silvery color, and becomes more slimy, the scales on the back partly sink into the skin, and the flesh changes from a salmon-red to a paler color. As the season advances, the differences between the males and females become more marked, in proportion as the milt is developed. The difference in the economic value of the spring and fall salmon, which is vastly in favor of the former, is dependent on the fact that the spring salmon enter the rivers long before the growth of the organs of reproduction has reduced the richness of the flesh, while the fall salmon can not be taken in quantity until their flesh has deteriorated. The quinnat is more valuable, on account of its size and abundance, than all the other fishes on the Pacific coast together; and the blue-back is worth much more than the combined value of the three remaining species. "It is the prevailing impression," say the authors of the report, "that the salmon have some special instinct which leads them to return to spawn in the same spawning-grounds where they were originally hatched. We fail to find any evidence of this in the case of the Pacific coast salmon, and we do not believe it to be true. It seems more probable that the young salmon, hatched in any river, mostly remain in the ocean within a radius of twenty, thirty, or forty miles of its mouth. These, in their movements about in the ocean, may come into contact with the cold waters of their parent rivers, or perhaps of any other river, at a considerable distance from the shore. In the case of the quinnat and the blue-back, their "instinct" leads them to ascend these fresh waters, and, in a majority of cases, these waters will be those in which the fish in question were originally spawned. Later in the season the growth of the reproductive organs leads them to approach the shore and to search for fresh waters, and still the chances are that they may find the original stream. But undoubtedly many fall salmon ascend or try to ascend streams in which no salmon was ever hatched." The evidence is not clear whether salmon are diminishing in numbers or not, except in the Sacramento River, where they are undoubtedly decreasing.

 

Storage of Electricity.—The reproach against electricity that it can not be stored seems now to be in a fair way of being removed by M. Camille Faure's recent improvement of the Planté secondary battery. The cells of this battery, as is well known, consist simply of two lead plates immersed in acidulated water, one of which becomes oxidized by the passage of a current through the cell, and is reconverted into the metallic state when the charging current ceases, yielding a current while undergoing this latter transformation. Once charged, the battery may be kept a considerable length of time without losing its power, and gives out a current steadily in a manner similar to an ordinary voltaic cell. The Planté cell is, however, not of commercial value, as its capacity is small, and it requires a considerable time to charge it. These difficulties M. Faure appears to have largely overcome by simply coating the plates with minium or red-lead, whereby their chemical dissimilarity, and consequently the electrical capacity of the cell, is greatly increased. When the charging takes place, the minium upon one plate is further oxidized to the peroxide, and that upon the other reduced to the metallic state, a current being given out while these plates are assuming their original condition. The cell is stated to give eighty per cent, of the current used to charge it, and to retain its charge for a considerable period. A battery containing four cells, and of the size of a cubic foot, was recent-