The Interstitial Granules of Striated Muscle etc. 345 



been obtained with cold alcohol. If the alcohol be heated the solution 

 must of course be cooled to room temperature before it is used. Freshly- 

 prepared stains usually give better results than those that are several 

 days old, a stain less than two hours old should be used to stain faint 

 liposomes. When a simple alcoholic solution is brought to maximum 

 efficiency, it will stain all but the very faintest liposomes; but since 

 it colors the protoplasm to some extent and does not clear the tissue, 

 the fainter liposomes are not so distinctly shown as with the Herx- 

 heimer solution, and are apt, to be overlooked. The Herxheimer solu- 

 tion does not seem to vary in its staining capacity. When using the 

 simple alcoholic solutions I have found it necessary to use the Herx- 

 heimer solution as a control in order to be sure that the former stains 

 are showing all the liposomes. 



On the other hand a simple alcoholic solution of Sudan III gives 

 better results than the Herxheimer solution on material that has been 

 fixed in potassium bichromate. It is also easier to stain the nuclei 

 after the simple alcoholic solution. 



I have confirmed the observation of Altmann that trïbutyrin 

 does not reduce osmic acid. Tristearin behaves toward the fat stains 

 in about the same way as palmitic acid. 



Cioccio [1909, 1910] has recently published papers in which a 

 modification of Weigert's myelin method is used to demonstrate certain 

 fatty substances in the tissues. This observor fixes the tissues 24 to 

 48 hours in the following mixture: 5 per cent potassium bichromate, 

 100 cc ; f ormaliii, 20 cc ; acetic acid, 5 cc. The tissue is then kept 5 to 

 8 days in 3 per cent potassium bichromate. It is ultimately embedded 

 in paraffin, and the sections are stained on the slide with a simple 

 alcoholic solution of Sudan III. Giaccio has shown that fatty droplets 

 may be demonstrated in a large variety of tissues by his method. In 

 his earlier papers he regarded the fat droplets shown by his method 

 as lecithin, but in a later paper [1910] the term lipoids (lipoidi) is 

 used. He believes that ordinary fats are unaffected by his fixative 

 and therefore dissolved by the fat solvents employed in embedding, 

 but that the lipoids are rendered insoluble so that they are not removed. 



