GRANULES AND FAT OF STRIATED MUSCLE 31 



four hours, these stains may color only a small part of the total 

 number of fat droplets which can be seen in fresh preparations 

 or demonstrated with Nile blue. Herxheimer ('04) does not state 

 specifically that his alkaline-alcoholic solution of Scharlach R 

 will color any fat droplets which cannot be stained with simple 

 alcoholic solutions but he quotes Erdheim ('03) as having made 

 such a claim. In so far as I have observed, alkaline-alcoholic 

 solutions of Scharlach R and Sudan iii stain all the fat droplets 

 of muscle fibers. Herxheimer's stain usually gives a deep red 

 color to droplets faintly stained or left colorless by simple alcoholic 

 solutions. As already stated, true interstitial granules are not 

 stained by Sudan iii and Scharlach R. Frozen sections or teased 

 preparations of muscle fibers, as well as of other tissues, which, 

 when stained by the ordinary stock solutions of Sudan iii and 

 Scharlach R in 70 per cent alcohol may appear fat free, are some- 

 times shown to be crowded with fat droplets when examined in 

 the unstained condition or when stained with Herxheimer's stain, 

 or with Nile blue followed by immersion in an alkaline medium. 

 In som.e specimens of muscle the simple alcoholic solutions stain 

 all the fat droplets which can be seen in the fresh tissue. 



The fact that fat droplets in muscle fibers are frequently left 

 unstained by the less concentrated solutions of Sudan iii and 

 Scharlach R does not seem to offer sufficient proof that such drop- 

 lets are not neutral fat. Fat in adipose tissue of mammals which 

 presumably is neutral fat, is occasionally colored so faintly by 

 these stains that were it in finely divided droplets it would be 

 almost colorless. I do not share the belief advanced by Bell 

 that we must suppose the droplets to contain an admixture of 

 albumin or other non-fatty substance. The droplets in the muscle 

 fibers of emaciated individuals, in so far as I have observed, stain 

 with as great intensity by Hei'xheimer's method as do those of 

 well nourished individuals. The intensity with which droplets 

 are stained both with Herxheimer's stain.and with simple alcohol- 

 lie solutions of Scharlach R depends as much upon the conditions 

 under which the dye is used as upon the nature of the fat. The 

 fact that droplets stain faintly cannot in itself be taken as suffi- 

 cient proof that they contain a non-fatty ejement. 



