The Interstitial Granules of Striated Muscle etc. 333 



Oct. 13. White rat. Weight 146 g. (Three other rats in the same 

 cage at this time showed only a few faint hposomes in the dark fibers, 

 and none at all in the pale fibers). Fed heavily on fat meat. Killed 

 October 24. Ten embryos not far from full term were found on section. 

 The muscle fibers contained an unusually large number of liposomes. 

 Every fiber was loaded, pale as well as dark fibers. The liposomes all 

 stained readily in Herxheimer's solution and in 80 per cent alcoholic 

 solution of scarlet red, but only those in the dark fibers were stained 

 by osmic acid. 



These experiments prove that the liposomes may be restored by 

 feeding, after they have been entirely, or almost entirely removed. 

 A diet of fat meat seems to produce more liposomes than a lean meat 

 diet. The liposomes .in the rat are readily influenced by the quantity 

 and quality of the food. 



Effect of fatigue. The gastrocnemius of a May frog (Rana pipiens) 

 in which the liposomes were nearly as strongly developed as those 

 shown in fig. 1, was completely fatigued by electrical stimulation^). 

 No differences could be detected between the liposomes of the fatigued 

 muscle and those of the opposite gastrocnemius. The food in the lipo- 

 somes seems not to be immediately available to the muscle fiber. 



Relation of the liposomes to the granules of Altmann. The fuchsin- 

 ophile granules demonstrable by Altmann's granule method include 

 a number of structures of widely different nature. The large Q-gran- 

 ules of the wing muscles of insects, and many secretory granules are 

 stained by this technique. These structures may be seen in the fresh 

 tissue. But Altmann's microsomes are not visible in the fresh tissue, 

 and it is easily possible that these are artefacts. It is known that 

 the size of protoplasmic granulations varies with the composition of 

 the fixative employed. 



Fuchsinophile granules may be shown in muscle fibers by Alt- 

 mann's method. These are commonly regarded as ordinary inter- 

 stitial granules. They lie in the sarcoplasm between the fibrils. Altmann 

 believed that the fuchsinophile granules were gradually converted into 



^) I am indebted to Dr. R. B. Gibson of the Department of Physiology for 

 the performance of this experiment. 



