86 



228. Bichromate mordantage, with subsequent copper or 

 iron hematoxylin stain, appears to rest upon the power of the fat or 

 lipoid to reduce the dichromate and thus take on a mordantage which 

 gives the basis for the subsequent staining. So far, it has not been 

 possible by this technique to preserve, in paraffin or celloidin sec- 

 tions, the individual fat granules, but it is nevertheless a useful 

 method for the differentiation of lipoid-containing cells. 



Fix tissue 2 days in Zenker's with but 1 /10 or 1 /5% of acetic acid 

 or Helly's fluid, mordant 4 days or longer in Muller's fluid at 35 to 

 38 C., wash in water, imbed in paraffin using chloroform as the clearer 

 (54). Stain sections with the copper hematoxylin ( 95). Lipoid- 

 containing cells, myelinic nerve fibers, erythrocytes, etc., a dark blue. 

 It should be also remembered that other structures may also be 

 stained by this technique. 



The freezing microtome may be used with such tissue and stain, 

 as has been done by Benda and Fischler [6]. 



B. Glycogen. 



Glycogen is soluble in aqueous media, and while it may be retained 

 by a short fixation in several fluids, the best preservative of it is 95% 

 alcohol (82% absolute). 



229. The Iodine Method. [16]. Fix tissue in 95% or 82% 

 alcohol. Imbed in paraffin. Spread the sections using instead of the 

 water, the iodine stain for glycogen, which is made up as follows: 

 iodin, \^/2 grams; potassium iodid, 3 grams; sodium chlorid, \}/<i 

 grams; distilled water, 300 c. c. Spread sections may be stained or 

 restained by immersing in the iodin solution which will color the 

 glycogen a mahogany red. For very soluble glycogen, 50% alcohol 

 may be employed instead of the water in making up the stain. In 

 mounting, dissolve the paraffin with xylene, drain, place on the 

 preparation melted yellow vaseline, cover, seal with shellac or balsam. 



230. Best's Method. [5]. While rather complicated, this 

 is generally recognized as the best method for the demonstration of 

 small quantities of glycogen, especially when it is desired to see the 

 relation of the granules to the protoplasm. 



Fix tissue in 95% alcohol; imbed (preferably) in celloidin (67); 

 if paraffin is used, after dehydration ( 51) place the pieces of tissue 

 in pure acetone for 15 minutes, xylene 20 minutes, xylene paraffin 

 1 hour, pure paraffin ( 52) 1 hour. Stain sections in Delafield's 

 hematoxylin ( 91) strongly, rinse and differentiate (if necessary) 

 and stain in the following special carmine stain which had been 



