112 Investigations on the Life-History 



10. THE NATURE OF THE PROTEIDS OF SALMON 

 MUSCLE. 



BY FRANCIS D. BOYD, M.D., F.R.C.P. ED. 



Dr. Dunlop, in his study of the muscles of the salmon during its 

 .sojourn in fresh water, finds that the proteids undergo a marked 

 diminution, being in part transferred to the growing ovary and testis, 

 and in part used as a source of muscular energy (p. 1 20). 



These observations, however, do not deal with the nature of the 

 proteids in muscle, and they leave unii instigated the question of which 

 proteids undergo this diminution. Since in the salmon we have an 

 animal undergoing a very prolonged fast, the subject seemed of interest in 

 relation to the pathology of starvation, and in view of results obtained 

 by previous observers in relation to this question. Thus the investiga- 

 tions of Tiegel (1), Buchart (2), and Salvioli (3) on the question of the 

 blood proteids during starvation have yielded somewhat contradic- 

 tory results, and do not enable us to arrive at any definite conclusion. 



Before considering the changes which the proteids undergo, it was 

 necessary to study the nature of the proteids which occur in the muscles 

 of salmon. 



This paper is thus divided into two sections A. The nature of the 

 proteids of salmon muscle. B. The changes which these proteids 

 undergo during the sojourn of the fish in fresh water. 



A. The Nature, of the Proteids of /Salmon Muscle. 

 2. Soluble Proteids. 



Method. (1) In examining the soluble proteids of the salmon muscle, a 

 portion of about 40 grammes of the flesh was taken, and all the bone 

 and visible fibrous tissue separated. The muscle was then minced, 

 pounded in a mortar, and extracted with normal salt solution. Normal 

 salt solution was used, as von Fiirth (4) has shown that stronger salt 

 solution possesses disadvantages, in that the proteids become altered 

 under the influence of the salt. It was found that all the soluble pro- 

 teid could be extracted by treating the muscle twice with normal saline 

 solution. The mixture thus obtained was filtered under pressure, the 

 filtrate got being a faintly opalescent fluid. The fluid gave all the pro- 

 teid reactions. No precipitation occurred on the addition of 1 per cent. 

 of a 33 per cent, solution of acetic acid. 



A. PROTEIDS COAGULABLE BY HEAT. 



An examination of the fluid extract gave the following result : 

 1. Dialysis. A quantity of the extract was put to dialyse in running 

 water. After 48 hours a copious precipitate was present This preci- 





