EXPLANATION OF PLATES. 



The drawings presented were all made from camera lucida outlines. Fat is repre- 

 sented in the characteristic red color obtained by the scarlet red method of staining fat. 

 All the drawings and outlines were made for me by Mr. George T. Kline, biological artist 

 of the University of Missouri. 



PLATE III. 



Fig. I. The transparency of a segment of dark muscle fiber of salmon no. 115 from the mouth of 

 the Columbia River, Ilwaco, Wash. The most superficial liposomes and fat droplets are represented 

 somewhat darker, while the paler colored droplets are deeper in the fiber. Magnification, Leitz ocular 

 2, objective 7. 



Fig. 2. \ small segment of dark muscle fiber from a j'oung salmon, from the Columbia River, 

 Warrendale, Oregon. Magnification, Leitz ocular 3, objective 7. 



Fig. 3. Section of trunk dark muscle of salmon no. 120, adult in prime condition from the Colum- 

 bia River at Warrendale, Oreg. The amount of fat present is almost as great as in the Ilwaco fish no. 

 Ill and no. 115. Magnification, Leitz ocular 2, objective 7. 



PLATE IV. 



Fig. 4. Trvmk dark muscle of salmon no. 126 from the Columbia River at Warrendale, Oreg. This 

 salmon is representative of a late stage in the fat removal from the tissues. Certain fibers near the 

 large blood vessel to the right are free of all but the smallest liposomes. Other fibers are still well sup- 

 plied with fat. Magnification, Leitz ocular 2, objective 7. 



Fig. 5. Dark muscle from salmon no. 138, a spawning salmon from the Clackamas River, Cazadero, 

 Greg. This figure represents the latest stages in fat removal from the trunk dark muscle. Magnification. 

 Leitz ocular 2, objective 7. 



PLATE V. 



Fig. 6. Transverse section of dark muscle from an exhausted, naturally spawned salmon no. 108, 

 McCloud River, Baird, Cal. This figure represents the extreme exhaustion of fat from the dark muscle. 

 The salmon was an enormous male which was taken just at the time of natural death. The fat is in 

 finest liposomes condensed at the surface of the fiber but absent between the fibers. The representa- 

 tion of the size of the liposomes is somewhat strong. Magnification, Leitz ocular 2, objective 7. 



Fig. 7. Dark muscle from young fish no. 97. The preparation is a paraffin section stained with 

 Mallory 's analine blue connective tissue stain. The figure presents well the excessive number of clear 

 spaces which represent vacuoles produced by extracting the fat in the imbedding process. One fiber 

 has recently divided longitudinally into two. This fiber shows no fat along the new portion of sarco- 

 lemma. Magnification, Leitz ocular 3, objective 1/12. (From American Journal of Anatomy, vol. 13, 

 1912, p. 175.) 



PLATE VI. 



Fig. 8. Trunk pink muscle of salmon no. 118 from the mouth of the Columbia River, Ilwaco, Oreg. 

 Attention is called to the great variation in the size of the fibers, to their characteristic outlines, the 

 great amount of fat between the fibers, and to the general distribution and extreme fineness of the 

 liposomes in the fibers, which have come out rather too strong in the reproduction, many of them 

 being actually just perceptible. This figure witliout the liposomes in the muscle fibers would represent 

 the normal condition of the salmon pink muscle at the beginning of the migration fast. Magnification, 

 Leitz ocular 2, objective 4. 



Fig. 9. Segments of two trunk pink fibers with adherent intermuscular fat drops from salmon no. 

 118. Magnification, Leitz ocular 2, objective 4. 



PLATE VII. 



Fig. 10. Trunk pink muscle of salmon no. 126 from the Columbia River at Warrendale, Oreg. This 

 salmon is the one presented as a typical poor condition fish. The intermuscular fat is reduced to groups 

 of droplets in the stronger connective tissue septa. The intramuscular fat is extremely low, limited to 

 the smallest and medium sized fibers. These fibers retain their normal histological structure as 

 shown in figure 13. Magnification, Leitz ocular 2, objective 4. 



137 



