The Interstitial Granules of Striatet Muscle etc. 335 



tissues for varying lengths of time (a few hours to several days) in an 

 iodine-potassium iodide solution. The granules shown in this way he 

 calls plasmosomes. He regards the plasmosomes as cell organs. Some 

 plasmosomes assimilate fat and become fat droplets. 



Arnold [1901] put pieces of elder pith (some of which were soaked 

 in milk, others in oleic acid) into the dorsal lymph space of a frog, and 

 found that some of the eosinophile granules of the leucocytes that come 

 into the pith take up fat, as is shown by their staining with sudan III. 

 If Arnold's observations be correct, he has shown that in the leucocytes 

 at least, fat droplets may be formed from préexistent protoplasmic gran- 

 ules, as was held by Altmann and Metzner. 



I have not studied the liposomes in the leucocytes, but I wish to 

 call attention to the fact that Arnold uses the same argument employed 

 by Metzner and Löwenstein to trace the origin of fat droplets from gran- 

 ules: viz, the presence of deeply-stained and faintly-stained droplets. 

 The mere fact that the fat droplets stain faintly when they first appear 

 does not prove that they come from the eosinophile granules. 



Some of Arnold's plasmosomes may be liposomes since many lipo- 

 somes persist for some time in his macerating fluid. 



Relation of the liposomes to the sarcosomes of Retzius. Retzius [1890] 

 worked largely with invertebrate muscle, and it is probable that many 

 of his sarcosomes are similar to the Q-granules of insect wing muscle. 

 He used chrom-osmic-acetic as a fixative. In discussing the effect of 

 fixatives in a preceding paragraph, it was mentioned that osmic acid 

 sometimes preserves liposomes some time without staining them appre- 

 ciably. It is therefore possible that some of the sarcosomes are lipo- 

 somes. 



The ultimate nature of the liposomes. Are the liposomes cell organs, 

 or are they merely metaplasmic substances ? It has already been shown 

 that the liposomes may all be removed (in rat muscle) by starving the 

 animal. During starvation they gradually become fainter and finally 

 disappear. They may be shown with Herxheimer's solution after osmic 

 acid no longer stains them. When the animal, whose muscle liposomes 

 have been entirely removed, is fed heavily on fat the liposomes reappear 

 in large numbers, and gradually increase in staining intensity. Even the 



