THE STORAGE OF FAT IN THE MUSCULAR TISSUE OF THE 

 KING SALMON AND ITS RESORPTION DURING THE FAST OF 

 THE SPAWNING MIGRATION. 



By CHARLES W. GREENE, Ph. D., 

 Department of Physiology and Pharmacology, Laboratory of Physiology, U niversity of Missouri. 



INTRODUCTION. 



To the present no study has been made of the distribution of fats in the muscu- 

 lature of the king salmon, Oncorhynchus ischawytscha. We have the classic studies of 

 Miescher" on the quantitative chemical variation in the fats of the Rhine salmon, 

 Salmo salar; also the studies of Noel Paton and his coworkers on the same species from 

 the Scottish rivers. Miescher found, as did Noel Paton after him, that there was a 

 great decrease in the quantity of fats as the fish ascended the rivers and as the spawn- 

 ing season approached. 



Miescher also observed fat in the muscle fibers in considerable quantity. This he 

 considered to be a stage of fatty degeneration preliminary to the use of the fats for the 

 building up of the immense store of food materials present in the salmon ova at the time 

 of spawning. Miescher states that the fat granules increase in numbers in midsummer, 

 and are absent after the salmon have spawned. He also states that the fats are practi- 

 cally absent in the fibers of the muscles of the smaller fins and of the head. 



Mahalanobis,* as a part of Noel Paton's series of studies, made a special histo- 

 logical examination of the fat in the muscles under the subtitle "Microscopic observations 

 on muscle fat in the salmon." There are six pages of text and seven microphotographic 

 figures presented in his paper. Less than two pages are used to present the findings 

 as to the distribution of fats in the muscles. He contrasts the variations in the fat 

 of "a fish fresh from the sea" with fish taken up the rivers at later dates. The greater 

 part of the text is consumed in a discussion tending to disprove the ' 'fatty degenera- 

 tion" theory which Miescher has assumed, and Miescher is undoubtedly in error 

 and Mahalanobis right in this particular matter. But Mahalanobis has failed in his 

 special comparisons between two extreme types of fish from the simple fact that he based 

 the comparisons on dissimilar muscles. (See p. 121 of this paper.) The studies on the 

 Atlantic salmon have, therefore, left us without adequate description of the normal 

 histological distribution of the muscle fats. As for the variations in the microscopic 



a Miescher, Friedrich: Statistische lind biologische Beitrage zur Kenntniss vom Leben des Rheinlachses im Susswasser. 

 Schweizerischer Fischerei-Ausstellung in Berlin, s. 154, 1880. Also reprinted in Die histochemischen und physiologischen 

 Arbeiten von Friedrich Miescher. s. 116. Leipzig, 1897. 



6 In; Paton, D. Noel. Report of the Fishery Board for Scotland. 1S98, p. 143. 



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