Page:Popular Science Monthly Volume 60.djvu/519

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THE BREEDING SALMON.

and clearness. The constituents of the genitalia are essentially different chemical compounds from the substances of the muscles out of which they are manufactured; yet the fact that their formation takes place wholly during the period of the animals' fast, leaves no other source for them. In the synthesis of these complex organic substances, the phosphorus—to mention only one element—can be traced with certainty back to the simple phosphates stored in the muscles of the salmon of the estuaries.

The mechanism by which this material is transported and transformed was the subject of much careful investigation by Miescher. lie noted a marked increase in the functional activity of the spleen—an organ as enigmatic in the salmon as in man. He observed also a decrease in the blood supply to those muscles at the expense of which the genitalia grow, and an equal increase to the genitalia themselves. The special significance of these conditions lies in the fact that a very small blood supply, continued through the summer and autumn, would transport many times the amount of material which actually becomes a part of the genitalia. As these organs are not motile, and are apparently the seat of no marked oxidation, their respiratory needs would appear small. Nature, however, follows closely the principle of 'least action'; and Miescher advanced the theory that, aside from its part in respiration, the oxygen brought to the tissues by the blood exercises a tonic influence upon their constructive processes. Thus in the liquefying muscle the lack of oxygen causes a stoppage and reversal of nutrition. The cell contents are absorbed into the blood. In the genitalia on the other hand the excess of oxygen in which the cells are bathed stimulates their nutritional processes, and results in vigorous growth. This view is, of course, a pure hypothesis. Yet it is interesting on account of its close similarity to theories advanced now, a generation later, by pathologists to explain the causes of abnormal growths in the tissues of man.

Important as are the results of the study of the salmon thus far mentioned, none rank in value with Miescher's investigations on the chemical nature of the sperm and ova. These researches were practically the first in which there was an attempt to lay bare the chemical processes involved in fertilization and the formation of the embryo. The clue which Miescher furnished has been followed by others, until to-day we seem to be approaching a determination of the structure of the proteid molecule—the first step necessary to solving the problem of the chemistry of living matter. Modern histology has shown that the fertilization of the ovum, from which the animal body develops, consists essentially in the entrance of the nucleus of the spermatozoon or male cell, and its fusion with the nucleus of the ovum. The nucleus of the spermatozoon must therefore be regarded as the carrier poten-