The Interstitial Granules of Striated Muscle etc. 317 



readily soluble in water it probably exists in aqueous mixture if present 

 in the tissues. A thick paste was made with water and smears were 

 stained with Herxheimer's solution. Only a faint red is obtained. 



Palmitic and stearic acids are solids at room temperature. In the 

 solid condition they are not stained by Herxheimer's solution. If the 

 staining be attempted at a temperature above the melting point of the 

 fat, the fat is quickly dissolved by the warm 70 per cent alcohol which 

 contains the Scarlet red. 7Ó per cent alcohol alone dissolves these fats 

 rapidly when its temperature is high enough to melt them. 



It seems that fats that are solid at ordinary temperatures cannot 

 be concerned directly in forming the stainable portion of the liposomes. 

 All soaps and fatty acids may be excluded, because invariably negative 

 tests were obtained with the methods of Benda, Fischler, and Klotz, 



The medullary sheaths of the nerve fibers stain a faint red with 

 Herxheimer's stain. Cerebrin, moistened with water, gives a similar 

 color. I have not tested any other fats. Probably others may be 

 found that stain faintly. However, the suggestion I offer to account 

 for differences in intensity of staining among the granules is the same 

 as that offered to explain differences in the refractive index, i. e., the 

 differences are quantitative rather than qualitative. The deeply- 

 staining granules contain a larger percentage of fats than those 

 that stain less strongly. Some additional evidence supporting this 

 view will be presented in connection with the inanition and feeding 

 experiments. 



2. Simple alcohoUc solutions of scarlet red and sudan III. The 

 varying strength of these stains has already been discussed. A large 

 excess of the dye (2 grams to each 100 cc. of alcohol) seems to give the 

 best results. These solutions often fail to stain a large number of faintly- 

 refractive liposomes. The color given the liposomes is seldom as intense 

 as that imparted by the alkahne solution. The alkaline solution has 

 the additional advantage that it clears up the tissue and makes the 

 granules much more readily visible. 



There is, however, no good evidence to show that the alkaline 

 solution will show fats qualitatively different from those brought 

 out by the simple alcoholic stains. Both stains g^ivtj' essentially the samt 



