Io8 BULLETIN OF THE BUREAU OF FISHERIES. 



from the blood vessel. Bordering on the opposite side of the same area there are two fibers which show 

 a verj' marked reduction in the number of liposomes next the vascular area, although the liposomes 

 are not altogether absent. The parts of the fibers opposite the area contain larger liposomes, i. 6 to 2 /i in 

 diameter. 



There is a very great variation in the amount of fat in different parts of this section (M25, teased), 

 if one is to judge by the microscopic size of the liposomes. Oil immersion examination of the dark 

 fibers shows numerous chains of liposomes ver>' similar in arrangement and appearance to slide M20 

 of trunk pink. The liposomes are more numerous than in the trunk pink, but the average size for the 

 center of the fiber is about the same. Many of these fibers show fat droplets on the surface under the 

 sarcolemma. Certain of the fibers show that the surface of the fiber has relatively large liposomes. In a 

 certain case near the superficial focus are liposomes 2 to 2.4 /( in diameter and near the center of the fiber 

 numerous smaller liposomes not over 0.6 y. in diameter with an occasional larger one 1.2 ji. The loading 

 of liposomes varies along the length of the fiber. This might easily happen in a tissue where the fat was 

 being eroded, since the arrangement of blood vessels can not be uniform with reference to the surface of 

 the whole fiber (fig. 4, pi. iv). 



Microscopic examination of the caudal dark muscle, slides M 16 and ly. — The intercellular fat has 

 disappeared, or is limited to a tiny droplet here and there in the connective tissue (1/12 oil immersion 

 examination). There are no larger drops or groups of droplets as in the trunk pink muscle. The myo- 

 commata still have some fat drops. 



The intracellular fat is present in the dark caudal muscle, but the liposomes are extremely small in 

 size. There are no fibers with the larger liposomes characteristic of the normal dark muscle. The 

 smaller liposomes average only 0.4 to 0.8 y.. In a small area which contains more fat, the liposomes are 

 larger, from 0.4 to 2 /( in diameter. These, liposomes are in a group toward one side of the fiber in an 

 area about 20 /t square. The center of tlie fiber has the smaller liposomes, and there is also a very marked 

 irregularity in the number in different parts of the field. 



In the above fiber and in four others in the immediate neighborhood there are small fat droplets 

 under the sarcolemma, measuring 2 to 3 /i, but in each case these droplets are on the side opposite the 

 adjacent blood vessels. The liposomes throughout the central portion of the fibers in fields in which the 

 fat is evidently sharply removed are reduced to scarcely distinguishable size, but are comparatively 

 numerous. On the surface of such fibers tlie liposomes are about 0.6 to o.S /; in diameter and also nu- 

 merous. Certain portions of the section show the fibers turned horizontally. Liposome chains can be 

 distinguished in these fibers. In one such fiber the liposomes of the chains are about 0.6 to 0.8 /; in 

 diameter. There are no fused liposomes in this case. This caudal muscle does not have more than 

 one-half to three-fifths the fat of the trunk muscle. 



DISTRIBUTION OF THE V htS AT A L.\TE INTERMEDI.\TE ST.-\GE OF THE SPAWNING MIGRATION. 



A Study was made of the amount of fat present in the tissues of salmon from the 

 Columbia River at the Celilo Rapids. These fish have passed through a longer stretch 

 of fresh water and through the relatively swift currents of the canyon of the Cascades. 

 The famous fishery of Mr. Frank A. Seufert extends along the full extent of The Dalles 

 of the Columbia." The numerous fish wheels adapted for the different stages of the water 

 make it an ideal collecting ground for scientific material. At the time of the visit to the 

 fishery in August, 1911, active fishing was in progress on the lower Dalles, at Celilo 

 Falls, and at the Tumwater seining grounds. The samples that were studied came from 

 a point known as the Cement Wheel, also from the seining grounds at Tumwater imme- 

 diately below the Celilo Falls. The Cement Wheel is about 300 yards above the mouth 

 of the Government canal. 



The Cement Wheel salmon will have battled only a short distance of the swifter 

 portion of the rapids of The Dalles. Two salmon were taken from this point, a male and 



o Mr. Seufert has always taken an active interest in the scientific questions concerning the propagation of the salmon and in 

 work tending to develop and protect the industry. He aided the present work by putting at our disposal every facility for 

 securing material in the best of condition. 



