Life-history of S Jmon. 113 



cent., during the later months the fats are almost the sole 

 source of energy. 



" 4. In the male, of the fat lost from the muscle to August 

 per cent, are accumulated in the testes, while 9-5 per cent, 

 are available for energy. Of the proteids 14 per cent, go to 

 the testes, leaving 8G 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 tlie female equivalent to 1,265,000 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 

 proteids of tlie muscle than in the male, where the fish is 

 comparatively poor in fats. Here the fats of 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 thi^ source" (p. 142). 



Dr. Paton has constructed a table wherein it is attempted 

 to show the work done by the female fish in ascending the 

 rivers Dee and Spey as compared with the energy evolved 

 from fats and proteids to August. An exact calculation is 

 impossible, but it is shown that for the raising of the fish's 

 body and the work of overcoming friction *' an enormous 

 surplus of energy is available from the combustion of the fat 

 and proteids which disappear from the muscles throughout 

 the sojourn of the fish in fresh water." It is also claimed by 

 Dr. Paton that his " observations very clearly prove that in a 

 coldblooded anima^ fats are a source of energy, and that they 

 p'ay a much more important part than the proteids ^^ — a con- 

 clusion adverse to that of Pfiiigerf, who has most strenuously 

 maintained the view that the proteids are the great source of 

 energy for muscular work (p. 142). 



Turning to carbohydrates, we find that in the present 

 investigations they have not been stuJied. Meischer Ruesch:):, 

 however, found small amounts of sugar present in the blooi 

 and liver and glycogen in the muscles even when the salmon 

 has been long in the river (p. 138). 



As regards phosphorus and its cjmpounds, the conclusion 

 is drawn that a supply, '* partly as inorganic piiosphates, 

 partly as k-cithin, is stored in the muscles as these grow and 

 become loaded with fat during the stay of the fish in the sea. 



" * The kilograminetre is the work done in lifting a kilogramme through 

 one metre. It is equivalent to 7'24 foot-pounds." 



t Arch. Bd. xlvi. 



X ' Histochemischen und phvsiologischen Arbeiten,' 1897, Bd. ii. 

 p. 325. 



