138 BULLETIN OF THE BUREAU OF FISHERIES. 



Fig. II. Trunk pink muscle from salmon no. 132, a spawning female from the Clackamas River, 

 Cazadero, Greg. The intermuscular fat is practically eliminated, yet all the fibers except the largest 

 show a considerable sprinkling of liposomes. In the small fibers these droplets are quite uniformly dis- 

 tributed, in the medium fibers concentrated around the surface, and in the largest fibers present only 

 in traces at the surface . The outline of the largest fiber to the upper right-hand side of the figure indicates 

 that it is approaching a degeneration stage, though the microscopic fibrillar structure is still normal in 

 appearance in this particular fiber. Magnification, Leitz ocular 2, objective 4. 



PLATE VIII. 



Fig. 12. — Cheek muscle of salmon no. 140, a spawned male from the Clackamas River, Cazadero, 

 Greg. Fat is present in a few groups of small droplets in the connective tissue septa. There is no intra- 

 muscular fat. One fiber in the center of this group is in an advanced stage of atrophy with pigmentation, 

 shown in the granules of this fiber (not to be confused with similar appearance of liposomes in other 

 figures). The three fibers to the right of this pigmented one show the first stages of degeneration rep- 

 resented by a swelling and blending of the fibrillae. This detail of structure is not shown in the figure. 

 Magnification, Leitz ocular 3, objective 4. 



Fig. 13. A highly magnified portion of a trunk pink fiber from salmon no. 126, Columbia River, 

 Warrendale, Greg. This small segment of a medium-sized pink fiber shows the normal fibrillar 

 arrangement. The amount of fat present is indicated in figure 10, plate vii. Traces of fat were pres- 

 ent in this particular segment just under the sarcolemma and between the outer series of fibrill^. 

 This figure is offered in evidence as showing that the elimination of fat from the pink muscle is not 

 accompanied by any immediate breaking down or degeneration of the finer structure of the tissue. 

 Magnification, Leitz, ocular 3, objective 1/12 oil immersion. Camera lucida outlines. 



PLATE IX. 



Fig. 14. The trunk dark muscle of young salmon no. 97 from the McCloud River, Baird, Cal. The 

 muscle fibers are drawn in outline to show the compact arrangement and relative size of the fibers as 

 compared with the adult. One particular fiber in this figure showed an exceptionally large fat drop in 

 the middle of the fiber. Magnification, Leitz ocular 4, objective 3. 



Fig. 15. Dark trunk muscle of salmon no. 126 from the Columbia River at Warrendale, Greg. 

 Drawing to show the outlines of the fibers of the adult fish after the fat is largely removed. This figure 

 should be compared with the preceding. Magnification, Leitz ocular 4, objective 3. 



PLATE X. 



Fig. 16. Outline of the trunk pink fibers of the young fish no, 97 from the McCloud River, Baird, 

 Cal. The figure shows outlines of the fibers at a stage in which active gro\vth is taking place. The large 

 number of relatively small fibers have recently split oft the larger in the process of fiber multiplication. 

 Magnification, Leitz ocular 4, objective 3. 



Fig. 17. Trunk pink muscle fibers from adult salmon no. 118 from the mouth of the Columbia River 

 at Ilwaco, Wash. The outlines of the fibers show the relative symmetry of the adult prime condition 

 muscle. The separation of the fibers is due to the loading of fat in the interstitial connective tissue. 

 Should be compared with figure 8, plate vi. Magnification, Leitz ocular 4, objective 3. 



PLATE XI. 



Fig. 18. Trunk pink muscle from salmon no. 122 from the Columbia River, Warrendale, Greg. 

 This outline figure shows the more compact arrangement of the fibers of pink muscle that has lost most 

 of its intermuscular fat. The fibers themselves are normal in outline. In this fish the pink fibers in 

 general seem somewhat smaller in size than the average for adult fish of mature size. This point should 

 be kept in mind in comparing the absolute size of the fibers shown in this figure and the preceding. 

 Magnification, Leitz ocular 4, objective 3. 



Fig. 19. Trunk pink muscle from fish no. 140, a spawning male from the Clackamas River, Cazadero, 

 Greg. The outlines of the fibers shown in this fish are typical of the stage just before natural death. The 

 larger fibers do not show any unquestioned structural signs of degeneration, though they have the 

 decrease in plumpness. Magnification, Leitz ocular 4, objective 3. 



