28 AMERICAN GAME FISHES. 



permit the introduction of food, except in very limited quanti- 

 ties, and Dr. Pancritius, of Germany, has very intelHgently 

 described the chemistry of digestion in fishes: so that these 

 subjects are problems no more. 



Possibly one reason why there has been such a wide diverg- 

 ence of opinion about the life-history of the Salmon is, that 

 there is nothing constant about them, except their periodical 

 visits to the sea and river, and these vary, not only with cli- 

 matic conditions, and the extreme diversity in the length of 

 rivers, but they are always liable to be disturbed by extrane- 

 ous contributory causes, such as sudden meterological changes, 

 erratic movements of the small fish and fry on which they 

 chiefly feed, raids of porpoises and seals, which split the 

 schools up into fragments, or drive the whole body off tempo- 

 rarily. In the Arctic rivers there is only a mid-summer run 

 of Salmon. There is no autumn run, for the rivers are 

 frozen tight by the end of September. In many Laurentian 

 rivers there are a spring, summer, and autumn run, because 

 the rivers are kept in full supply of cold water from the reser- 

 voirs of melting snow at their sources. In rivers of extreme 

 length, like the Columbia, Yukon, and others of the Pacific 

 coast, the spring run of Salmon does not go back to the sea, for 

 obvious reasons. If the fish have five hundred miles or more 

 to ascend, they cannot afford to lose time by running in and 

 out. High falls especially retard their progress. To sur- 

 mount these they are obliged to climb their rugged abutments, 

 which are full of pockets and crevices and projections, over 

 which the lateral overflow is constantly spilling in greater or 

 less quantity; and it is not altogether an impossible feat for 

 a Salmon to mount a very high fall by these gradual steps, 

 stopping betimes to rest his muscles and moisten his gills in 

 the little basins which present themselves conveniently at 

 hand. But they will not essay this side-passage until they 

 have persistently attempted to leap the breast of the fall; 

 hence, some careless observers have maintained against all 



