142 



Investigations on the Life-History 



4. In the male, of the fats lost from the muscle to August, 5 percent, 

 are accumulated in the testes, while 95 per cent, are available for energy. 

 Of the proteids 14 per cent, go to the testes, leaving 86 per cent, 

 as a source of energy. 



5. In the period to August, when male and female fish can be compared, 

 the energy liberated per fish of standard length was, in the female, 

 equivalent to 1,205,000 Kgms.,* while in the male it was equivalent to 

 1,380,000 Kgms. In the female, where fat accumulation in the ovaries is 

 large, a greater proportion of energy appears to be derived from the pro- 

 teids of the muscle than in the male, where the testes is comparatively 

 poor in fats. Here the fats of the muscle yield a larger proportion of 

 energy than in the female. In the female to August, of the total 

 available energy, about 20 per cent, is derived from the proteids, while 

 in the male only 9 per cent, is obtained from this source. 



In ascending the river the salmon has not only to raise its weight to 

 a given height, but it has to overcome the friction of the stream. 



The former factor in the expenditure of energy is easily calculated if 

 the elevation of the upper waters of the river is known. 



The following Table gives the elevation of the upper waters of the 

 three rivers, and the work done in raising a fish of standard length 

 and average weight 10 Kg.s. 



The energy employed in merely lifting the weight of the fish is to the 

 whole energy expended as 1 to 570. 



An enormous surplus of energy is thus available for the work of 

 overcoming friction. To form anything like a correct idea of what this 

 may be is at present impossible, for information as regards the rate of 

 progress of salmon is wanting, and the work done by the fish will 

 necessarily vary with the rate at which the upward progress is made. 



But these figures show that for this work an enormous surplus of 

 energy is available from the combustion of the fats and proteids which 

 disappear from the muscles throughout the sojourn of the fish in fresh 

 water. 



Pfliiger has recently (Pflttg. Arch. Bd., XLVI.) most strenuously 

 maintained the view that the proteids are the great source of the energy 

 for muscular work. The present observations very clearly prove that, 

 in a cold-blooded animal, fats are a source of energy, and that they play a 

 much more important part than the proteids. 



* The Kilogram met.re is the work done 

 equivalent to 7'24 foot-pounds. 



in lifting a Kilogramme through one metre. It is 



