GRANULES AND FAT OF STRIATED MUSCLE 41 . 



nutritive condition of the animal. Bell ('11) found that the 

 liposomes (fat droplets) of the striated muscle fibers of rats were 

 entirely removed when the animal was starved until it had lost 

 25 per cent or more in body weight. During starvation, the lipo- 

 somes gradually became faintly refractive and decreased in size, 

 number and in staining intensity with Herxheimer's Scharlach 

 R and with osmic acid. When the starved animal was again 

 given food the liposomes gradually reappeared, increasing in 

 size, number, refractive power, and staining intensity as the animal 

 gained weight. In normal rats which were fed on fat meat for 

 several days, the liposomes were greatly increased in number, 

 size, and staining intensity. When summer frogs were fed heavily 

 on olive oil or fat meat, there was a striking increase in size, num- 

 ber and staining intensity of the liposomes. No changes were 

 produced in the liposomes by the feeding of grape sugar, starch, 

 palmitic acid, sodium oleate, or lean meat. Since the liposomes 

 stained faintly when they first appeared, Bell supposed that they 

 then contained a relatively small percentage of fat together with 

 some substance other than fat, possibly an albumino-lipoid. He 

 regarded the liposomes as foci where fat is deposited and concluded 

 that they consist of reserve food substances mainly, at least, in 

 the form of fats. 



In this connection I have examined the muscle fibers of a dozen 

 white rats on various nutritive planes. Figure 1 represents 

 fibers from the pectoralis major bi an adult rat which had been 

 heavily fed on fat meat for seven days. The fat droplets were 

 stained with Herxheimer's Scharlach R. Figure 2 shows muscle 

 fibers from the pectoralis major of a rat which had been kept for 

 ten days on short rations of a fat free diet consisting mainly of 

 cellulose. Fat cells were almost completely absent from the sub- 

 cutaneous tissue and mesentery of this animal. Fat droplets are 

 practically absent from the light fibers as shown in the figure, 

 while dark fibers have a smaller quantity of fat than is normally 

 present even in light fibers. In the diaphragm of this animal, the 

 quantity of fat, although greatly reduced from the normal, was 

 somewhat greater than that found in the pectoralis major. 



The amount of fat in the cardiac muscle fibers of emaciated 

 rats was less than in fibers of well nourished individuals. Animals 



