5IO POPULAR SCIENCE MONTHLY. 



consumed by tlie salmon in accomplishing the distance, it would be 

 easy to reach fairly exact conclusions in terms of distance traveled, 

 weights transported and fuel expended by the salmon, and to 

 compare these results with those accomplished by a steamship; or to 

 calculate the resistance of the water overcome by the salmon, and 

 from this compare the relative advantages of the 'lines' of a salmon 

 and those of a racing yacht. There can be little doubt that in the first 

 case the advantages would be heavily on the side of the salmon, and 

 that the yacht would show little if any superiority. But leaving aside 

 such theoretical considerations — for which, it is only just to say. Dr. Noel 

 Paton and his coworkers are in no way responsible — the investigations 

 on the Scottish salmon show that eighty to ninety per cent, of the 

 energy liberated by them in the muscular work of swimming is derived 

 from the fats. The hungering salmon, like a hungering man or dog, 

 reduces to a minimum the waste of protoplasm — that peculiar jelly 

 of albuminous substances which constitutes the chemical framework 

 and essential mechanism of the living cells of the body. In the salmon 

 ascending a river, as in a man ascending a mountain, the energy 

 liberated in the work done is supplied by a vigorous oxidation, and 

 this is evidenced by an increased absorption of oxygen and excretion 

 of carbonic acid. The elimination of nitrogenous substances from 

 the waste of the tissue proteids is, however, only slightly increased. 



No less interesting are the processes by which the genitalia develop, 

 since they afford an example of constructive activity almost without 

 parallel among animals; processes so characteristic of plants, on the 

 contrary, that they were long supposed to exhibit the generic differences 

 in the vital mechanism in the plant and animal kingdoms. Modern 

 research has, indeed, shown that these great apparent differences are mat- 

 ters of degree, not kind. Plants can not now be considered as devoted 

 solely to absorbing carbonic acid, and by means of the heat and light of 

 the sun synthesizing carbonaceous material. They can, and when need 

 arises, they do draw on their store of fuel, exhale carbonic acid, and 

 even liberate measurable quantities of heat. On the other hand, 

 physiologists have come to admit that the cells of the animal body, 

 although wholly dependent on the vegetable kingdom for their ma- 

 terials and energy, yet possess wide powers of transforming the food 

 substances to their needs. Uncertainty has, however, attended the 

 efforts of the investigator of metabolism in man and the higher animals. 

 Generally when the subject of the experiment fasts, growth stops. If 

 on the other hand the subject is fed, the origin of the substances shown 

 to appear or increase in any tissue — for instance the fats — may be 

 assigned with almost equal chances to any one of the constituents of 

 the food, or to a transportation from other tissues of the body itself. 

 In the salmon, on the contrary, the conditions are of extreme simplicity 



