The Interstitial Granules of Striated Muscle etc. 347 



Giaccio. It is therefore probable that some of the small solid droplets 

 and larger ring droplets described by Giaccio consist of triolein. 

 But the larger solid droplets shown by Giaccio 's method cannot 

 consist of pure triolein. This technique is a valuable addition to 

 our histological methods, but it gives only a rough distinction bet- 

 ween the neutral fats and the hpoids. 



I have used the Giaccio method on a number of tissues. It gives 

 excellent results on medullated nerves, the fat droplets in some leuco- 

 c^i;es, and the doubly-refractive fat of the adrenal. It brings out part 

 of the fat in the kidney. In rat muscle I have succeded in showing 

 the liposomes only once by this technique, and in this case they were 

 very faint and much less numerous than in the fresh tissue. But by 

 modifications of the Giaccio method suggested by Smith's paper it is 

 possible to stain a large part of the liposomes in paraffin sections. 

 In place of Giaccio's fixative I use 10 per cent potassium bichromate 

 at 37° G for 24 to 72 hours. The material is then embedded in paraffin 

 and stained on the slide with Sudan III in simple alcoholic solution. 

 As might be expected from Smith's work, the bichromate treatment 

 must be varied in accordance with the particular fat that is to be 

 fixed. No general bichromate treatment can be recommended for all 

 fatty droplets. 



The results obtained by Smith and Giaccio are not against the 

 probability expressed in the body of this paper that the muscle lipo- 

 somes often contain triolein as the chief stainable component. 



