122 BULLETIN OF THE BUREAU OF FISHERIES. 



partly at least in the Q-band. In many fibers the granules are arranged in distinct transverse rows, 

 being apparently limited by Krause's membrane. 



The nature of the muscle granules and particularly of the liposomes has been 

 extensively studied by Bell. But as the question of the kind of fat has not been espe- 

 cially investigated in the salmon muscle the review of the discussion will be omitted at 

 the present time. The contributions by Bell that are of special and far-reaching value 

 in relation to the questions involved in this paper are two: First, the influence of star- 

 vation on the fat content of the muscle tissue; second, the influence of fat feeding on 

 the number and size of the liposomes of the muscles. Under the subject of lack of food. 

 Bell says: 



In every animal there is a gradual disappearance of the liposomes during inanition. As the animal 

 loses weight the liposomes gradually become smaller and less refractive ;. and they also stain with decreas- 

 ing intensity. The muscle fibers of a well-nourished cat are usually full of coarse deeply stained drop- 

 lets such as is shown in figure i, from the frog. 



Also: 



In the rat there is a very rapid decrease in the number, size, refractive power, and staining intensity 

 of the liposomes. A well-fed rat may contain a large number of strongly refractive liposomes in its 

 muscle fibers, many of which may be stained with osmic acid. After a reduction in the body weight of 

 15 to 20 per cent only a few faintly refractive liposomes are usually left. After a reduction of 25 to 30 

 percent, it is often foimd that no liposomes at all can be demonstrated. Every liposome has disappeared. 



The remarkable sensitiveness of the liposomes in rat muscle to the food supply imdoubtedly accounts 

 to a considerable extent for tlie large variations one finds in animals gathered at random. It will be 

 shown, however, later that the quality of the food is a factor of almost as much importance as the quantity. 

 A rat whose bodj' weight has been reduced 25 to 30 per cent may develop a large number of deeply 

 staining liposomes m its muscle fibers 1 if fed on a diet largely composed of fat meat) though the body 

 weight remains far below normal. 



There is, as has been sho^^^l, a marked difference in the number and character of the liposomes of a 

 well-nourished normal animal and those of an emaciated animal; but the liposomes of an animal in 

 ordinary condition may not differ essentially from those of a very fat individual. No particular differ- 

 ences were noted between the muscle liposomes of steers, in which the subcutaneous fatty layer was 

 6 cm. thick, and those of steers in which this layer was only 5 mm. thick. It was also noted in rats and 

 dogs that excessive amounts of connective tissue fat are not coordinated with excessive development of 

 the liposomes. 



It is however clear from the above-described disappearance of the liposomes during inanition that 



they consist of some form of reserve food substance. This conclusion is in accord with the view that 



.they consist of true fats or fat-like substances. The gradual decrease in the refractive power and 



staining-intensitj' of the liposomes indicates that the fats are mixed in the liposome with some substance 



other than fat. 



Under the topic of "The effect of special feeding on the liposomes" Bell says: 



Some interesting results were obtained by feeding summer frogs on special rations. It has been 

 pointed out above that in the summer months (June, July, and August) the muscle fibers contain very 

 little fat. In a great many animals, in July and early August at least, no liposomes at all can be 

 demonstrated in the light fibers, and those Ln the dark fibers are very small and faint and can only be 

 stained with Herxheimer's solution. Some young frogs were found in which no liposomes at all could 

 be shown. It was foimd that when frogs in this condition were fed heavily on olive oil or fat meat for a 

 few days the fibers become loaded with liposomes, giving a picture similar to that found in winter 

 animals. 



Bell also tested the fat content of the muscles of frogs caught in the field showing 

 that the muscles of leopard frogs before feeding had a "few faint liposomes in the dark 

 fibers, none in the light fibers," but after feeding with fat meat and olive oil all the 



