THE SALMON, TIIE TROUT, AND THE SHAD. 747 



knocked on the head, and that their stomachs never contain remnants 

 of food, militates against that supposition. All the fishermen whom I 

 questioned assured me that they never had found food in the salmon 

 even if cut open immediately after having been caught. 



In view of this remarkable fact, two questions naturally arise: 1. 

 How can the salmon live for a comparatively long time without food 

 without (as is the case at least with the winter-salmon) growing visibly 

 thinner % 2. How does it happen that the salmon does not eat any more 

 after having entered fresh water ? The first of these questions is less 

 difficult to answer than the second. I shall now briefly examine the 

 first. 



It is well known that the change of matter (Stoffwechsel) and the heat 

 of the animal body resulting from it reach their highest degree in birds 

 and mammals, but that they are much less in amphibious animals and 

 fishes, because the organs of respiration and of circulation are much less 

 complete in those vertebrates than in the two higher classes. This also 

 explains the well-known fact that amphibious animals and fishes can. 

 live without food for a much longer time than the higher vertebrates. 

 This circumstance, however, does not yet sufficiently explain the fact 

 that the salmon can live so long without food without growing visibly 

 thinner, as the winter-salmon. One might feel tempted to think of 

 the somewhat analogous winter-sleep of many animals, if this was not 

 made impossible by the violent motions of the salmon. If the swim- 

 ming and leaps of the salmon, like every motion of this kind, are noth- 

 ing but a change from the molecular to the mass motion, and if this 

 molecular motion can only be the result of a burning process, there must 

 be some matter which makes such a burning process possible ; and if 

 this matter is not, as is usually the case, supplied by the taking of food, 

 the body itself must furnish it ; and this is actually the case with the 

 salmon. As regards the winter-salmon, I have stated above that its 

 stomach is surrounded by a very considerable mass of fat. This fat 

 forms, so to speak, the reserve fand from which the expenses of this 

 burning process are paid. This fund is large, and lasts long enough 

 to make the winter-salmon during all the time of its sojourn in the 

 Ehine (which is not as long as is generally supposed) a highly-esteemed 

 fish. 



The case is different with the spawn- salmon. When it ascends the 

 Ehine, its eggs are already as large as pease, and the milt is almost ready 

 for impregnating. Even while out in the ocean, the inner organs were 

 chiefly engaged in developing the eggs and the milt. On entering the 

 Ehine, it is well developed, but compared to the winter-salmon it has 

 only a small reserve fund. This is considerably diminished by the very 

 violent motions of the fish, and the remainder is so completely used up 

 in fully forming the sexual organs that the quality of the flesh deteri- 

 orates considerably, and the fish becomes weak and miserable. It is, 

 therefore, not astonishing to see these fish, after having finished spawn- 



