102 BULLETIN OF THE BUREAU OF FISHERIES. 



red dye. Rather it is a more brilliant and dark appearing neutral red. The amount 

 of stain taken is only slight. These granules do not contain any pigment, as was 

 noted in degenerating cheek muscle of fish no. 140, to be described later. 



PROTOCOLS. 

 Male, salmon (no. 120), length g^J mm., weight 11,480 grams, Warrendale, August 16, igil. 



This fish was taken from the McGowan seining grounds, iK miles below Warrendale. It was a fine 

 fish, in splendid condition; the nose slightly hooked, no large teeth, the testes two-tliirds developed, 

 color normal, but a trace darker than fish at the mouth of the river; back darker but not rusty; fins 

 perfect. 



The muscles were pink and oily. The fish was received fresh from the seining grounds, and the fin 

 muscles were still alive when samples were taken. 



Microscopic examination of the trunk pink muscle {KS/, SS, and go). — The intermuscular fat is about 

 one-half to two-thirds as great as in no. 118 from Ilwaco. Its disposal between the fibers is similar to 

 the fish taken from the mouth of the Columbia. There is less intermuscular fat from the middle of 

 the dorsal portion of the great lateral muscle. 



The intramuscular fat is abundantly present in all of the fibers. The smaller fibers are more deeply 

 stained, showing the greatest amount of fat. The small fibers of the teased preparation are filled with 

 chains of liposomes, the individiial liposomes being larger than in the large fibers. In the fibers of large 

 size the chains of liposomes are not quite so numerous, and the liposomes themselves arc relatively 

 small. Two fibers, side by side, one large and the other small, are in sharp contrast. 



Microscopic examination 0/ the caudal pink muscle (transverse section, Kgi). — In this section the inter- 

 muscular fat is all gone except along the connective tissue septa, where it is present in scattered but 

 medium large drops (1/12 oil immersion). The substance of these fibers is well fixed in formalin, and 

 the fibrillar outlines show clearly. In the large fibers of the section there is no fat stain in the body of the 

 fibers. Occasionally at the very surface there are tiny groups of liposomes. In the smallest fibers there 

 are in the body of the fibers between the fibrillse numerous extremely small liposomes. There are dis- 

 tinct masses of liposomes on the surface of the sarcoplasm and under tlie sarcolemma. The liposomes 

 within the fiber are from 0.2 to 0.4/! in diameter, those on the surface from i to i.5,h in diameter. The 

 intermediate-sized muscle fibers have a few scattered groups of liposomes immediately under the 

 sarcolemma, but none in the body of the fiber. These observations are confirmed on fragments of 

 fibers in which the fibrillae are turned in a horizontal position. 



Microscopic examination of the trunk dark muscle (sections Kj2-j6). — The muscle fibers in this 

 material, both in the transverse sections and in the teased preparations, are especially richly supplied 

 with fat. The fat is crowded, both between the fibers and throughout the sarcoplasm of the fibers. 

 The intermuscular fat droplets are numerous, of medium size, bxit not so numerous nor so large as in 

 fish no. Ill from the Ilwaco station. 



Certain areas in the transverse section have an appreciably smaller quantity of fat. These areas 

 are associated with connective tissue septa carrying blood vessels, and are similar to tliose noted in 

 salmon no. 117 and no. 118, from the mouth of the Columbia. This appearance is undoubtedly 

 due to the beginning of fat erosion from this type of muscle, and is greater in this section than in the 

 two Ilwaco fish referred to. The erosion areas have a much less quantity of fat than in fish no. 118. 

 The fat droplets are not so numerous and are smaller. 



On the whole, the amoimt of fat is somewhat less than in fish no. 118, though the comparison is 

 difficult to make. In the transverse section of one fiber 100 /i in diameter, 46 droplets were counted. 

 They were from 3 to 6// in diameter. In the spaces around the particular fiber and in the same focal 

 field were 12 droplets oval in shape, 20 /i long, but from 4 to 6 a thick. 



The intramuscular fat is remarkably uniform in its distribution through the muscle fiber, the larger 

 droplets averaging from 4 to 6 /i in diameter. The disposal of the fat is similar in character to that noted 

 in previous fish and is shown in figure 3, plate iii. 



Microscopic examination of the caudal dark muscle. — The muscles in this section have very much 

 less fat than the trunk dark fibers. The intermuscular fat is smaller, 6 to 10 /( in diameter, but the 

 droplets are numerous. 



