STORAGE OF FAT IN MUSCULAR TISSUE OF KING SALMON. 



"5 



On the whole, they confirm the microscopic findings. It is unfortunate that no fat 

 percentage determinations were made on no. 140, the only salmon that presented in 

 the masseter muscle definite and unmistakable evidence of muscle degenerations. This 

 series should be compared with the Ilwaco series in table i, page 92. 



Table II. — Analytical Determinations of F.\ts in the Tissues of Certain Salmon from 

 Clack.\mas River, Cazadero, Greg., taken September, 19 ii. 



protocols. 

 spawning female salmon {no. 132), length g6o mm., weight 6,840 grams (after artificial spawning). 



External appearance first class, body slender in form. An appreciable oedema of the inner surface 

 of the body cavity walls. Visceral mass exceptionally small. 



Microscopic examination of the trunk pink muscle. — In a small portion of section N47 there is a very 

 small quantity of intermuscular fat, but in general neither the connective tissue septa nor the thicker 

 strands separating the fibers have more than tiny liposomes. There is a sharp contrast between this fish 

 and no. 127 from Celilo in this regard. These fat droplets in the connective tissue measure a maximum 

 of 5 to 6 /i. The average size is very much smaller, between i and 2 ;i. The trunk pink fibers of this 

 salmon are somewhat more plump and round in outline than in no. 131. All the larger fibers, however, 

 are compressed and irregular in outline, suggesting the same type of change noticed in other relatively 

 fat free tissues. 



There is intramuscular fat in the smaller fibers and in the medium in the form of liposomes. These 

 liposomes are distributed rather uniformly through the substance of tlie smaller fibers. In the medium- 

 sized fibers there are not so many liposomes and tliey are much fewer in tlie center of the fibers. Around 

 the circumference of the fibers and under the sarcolemma there is more fat, especially under the sar- 

 colemma. These small and intermediate fibers have sometimes almost complete rings of fat droplets 

 under the sarcolemma. The largest fibers have a greatly reduced quantity of fat. The fat is in very 

 much smaller liposomes, often scarcely visible. Around the surface and under the sarcolemma there 

 are groups of fat droplets, but not so plentiful as in the medium fibers. 



This material on the whole is characterized by the small amount of intermuscular fat and the rela- 

 tively great amount of intramuscular fat. In some portions of the sections the intramuscular fat is as 

 great as in fish no. iiS from Ilwaco, far greater than in no. 126 from Warrendale or no. 127 from Seuferts 

 Cement Wheel. The uniformity of distribution of the fat is not so great as in the Ilwaco specimens. 



Microscopic examination of the caudal pink mttscle. — There is no intermuscular fat in this section 

 (N59). In the myocommata shown there is a trifle of fat just at the surface. 



The muscle fibers have some intramuscular fat, but the relative amount in the different types of 

 fibers is difficult to determine, on account of the excess of precipitate present. Some of this so-called 

 precipitate is in characteristic round granules like unstained fat, but some of it is in the characteristic 

 scarlet red color, interpreted as a less successful staining manipulation. 



Microscopic examination of tlie trunk dark muscle (slides Nsssy). — These sections all show a rela- 

 tively small amount of fat in the myocommata. 



The muscle tissue as a whole shows much fat in the critical region at the surface of and between 

 the fibers. Under the oil immersion it is apparent tliat a large amount of this fat is between the fibers 

 in droplets from 2.5 to 3 /j in diameter. The muscle fibers are so compact in arrangement that it is diffi- 

 cult to identify the exact limits of the fiber. Certain unquestioned regions show this fat between the 



