120 //trevtigations on the Life-History 



11. THE CHANGES IN THE AMOUNT OF PROTEID 

 IN THE MUSCALATURE AND GENITALIA OF 

 SALMON IN FRESH WATER. 



BY JAMES C. DUNLOP, M.D., F.R.C.P. ED. 



A study of the changes which the proteids of salmon undergo during 

 the time of its ascending rivers and during its stay in fresh water is 

 of interest, not only to those concerned with the marketable 

 value of salmon as a food stuff, but also to the physiologist. In 

 salmon we have an example of an animal which is required, during a 

 long period of starvation, to do a large amount of muscular work, and 

 at the same time to supply a large amount of substance for the require- 

 ments of rapidly developing genitalia. Proteid is certainly required 

 for the growth of the genitalia, and almost as certainly for the pro- 

 duction of some of the energy for muscular work, and for the necessary 

 repair of the energy-yielding mechanism, the muscle ; and so the 

 question arises as to whether the salmon has in itself a sufficiency of 

 proteids to supply these wants when it leaves the sea. Does a com- 

 parison of the fish after their stay in fresh water with fish captured in 

 the estuary as they come from the sea warrant the conclusion that 

 they have been obtaining the proteid required for these purposes from 

 their own tissues ? 



Should there exist a store of proteid in fresh run salmon, 

 it is natural to look for it in the musculature, which is so rich 

 in proteid, and which forms such a large amount of the total weight of 

 the fish. Consequently in this research the proteid of muscle has been 

 fully examined. Of the great requirements for proteids mentioned 

 above, one only, the growth of the genitalia, lends itself to measure- 

 ment, and consequently it is this which is here specially considered, 

 and any proteid consumption not accounted for by it is put down to 

 the other great requirements, the supply of muscular energy .and repair 

 of the energy-producing mechanism. 



A point of physiology, on which this study has a direct bearing, is how 

 far the proteids of one tissue can be called on to supply the wants of 

 another. If this examination of salmon shows that the proteid wants 

 of the genitalia are supplied from the proteids of muscle, it indicates 

 a very large transference from one tissue to another. 



The subject has been previously studied by Miescher Ruesch 

 (Internationale Fisherei-Austellung zu Berlin, 1880). He concluded that 

 a fresh run salmon has an ample store of proteid to meet all its 

 requirements in fresh water. The objections to Miescher's work have 

 been considered in another portion of this Report (page 80). He gives 

 percentage analyses of the proteids in a series of fish, but he made a 

 definite quantitative analysis of the total amount, of muscle proteid in 



