METABOLISM OF THE SALMON. 375 



Ruesch as a degeneration, but this conception of the process 

 is not supported by histological examination. What occurs 

 is an accumulation of fat outside and within the fibres while 

 the fish is feeding, and this is subsequently, during the 

 inanition period, used up for the construction of the geni- 

 talia and as a source of muscular energy. 



The " curd " of salmon muscle which is so marked in the 

 fish just leaving the sea early in the year is composed of 

 proteids and fats. 



The nature of the proteids in the muscles was investigated 

 by Dr. Dunlop. He finds paramyosinogen, myosinogen, 

 and myoglobulin which are all soluble in salt solution ; a 

 nucleo-proteid corresponding to that found by Pekelharing, 

 and called myostromin by Karajew ; this is partly soluble 

 in salt solution, and wholly so in 1 per cent, caustic soda 

 solution. Collagen from the interstitial connective tissue 

 was not dissolved by either reagent. True albumin was 

 not found, and proteoses and peptose were also absent. No 

 mention is made of what v. Fiirth calls myo-proteid, and 

 which he considers to be characteristic of fishes muscle, nor 

 of Siegfried's nucleon. It is apparently the soluble proteids 

 which undergo the diminution demonstrated to occur as the 

 fish proceeds to the upper waters. 



Coming now to the summary of metabolic exchanges in 

 fat and proteid, we enter the region of controversy ; and in 

 view of the recent discussion by Pfluger and others of the 

 part played by fats and proteids respectively as a source of 

 muscular energy, the present observations on a cold-blooded 

 animal in which the decomposition of the fats can be only 

 sparingly connected with the^ evolution of heat, are of no 

 little interest. 



If the fat and proteid going to the ovaries and testes is 

 subtracted from that lost from the muscles, the residue 

 gives the amount available for the liberation of energy. 

 The absolute numbers are given in the report, but it will 

 be sufficient here to mention the proportion found. In 

 female fish up to August the energy from proteids to 

 energy from fats is as 1 : 4 • 2 ; extending the observations 

 to November the proportion rises to 1 : 7 ' 6. In male fish 



