222 Biological Stains 



not mixed with the stain, but is used for a preHminary mordanting 

 of the tissue. 



Hematoxyhn has been combined with chromium, one of the 

 early staining methods. being that of R. Heidenhain (1886), which 

 called for potassium bichromate as a mordant. Various recent 

 modifications are in use today, such as that of Apathy (1888), for 

 staining general tissue. Weigert (1884) used a chrom combina- 

 tion for staining nervous tissue. 



Benda (1893) employed hematoxylin following treatment with 

 a copper salt for studying spermatogenesis; and Bensley (see 

 Guyer, 1936, p. 164) a similar technic for chromosomes and mito- 

 chondria. A formula containing logwood extract, with alum and 

 copper sulfate was suggested by Cook (1879). 



Mallory (1938, p. 156) proposed a formula for hematoxylin con- 

 taining phosphomolybdic acid and also one containing phospho- 

 tungstic acid. The latter method is especially valuable for stain- 

 ing cells in the process of mitosis, and for distinguishing fibroglia, 

 myoglia and neuroglia fibrils from collagen and elastin fibrils, 

 especially in tumors, but also in normal tissues. It brings out 

 sharply the striations in skeletal and cardiac muscle fibers. Hema- 

 toxylin is used in combination with other stains, especially eosin, 

 but not so frequently as in the case of the common anilin dyes. 

 The Van Gieson technic calls for hematoxylin followed by picric 

 acid and acid fuchsin. A few other methods call for picric acid or 

 ammonium picrate after hematoxylin: and it is sometimes used 

 with eosin or after orange G or acid fuchsin. Most of these com- 

 binations, however, are called for only in the case of special pro- 

 cedures. 



Isohematein. If hematein is treated with HCl in sealed tubes 

 at 100°C and then treated with silver hydroxide to remove the 

 chlorine, a solution is obtained of a compound known as isohem- 

 atein, which can be secured as an amorphous mass by evaporation. 

 At the request of the Stain Commission, an American manu- 

 facturer of logwood products actually prepared an experimental 

 batch of isohematein by this method, and Cole (1931) reported on 

 its use as a biological stain. The result of this study was to in- 

 dicate that it could hardly replace hematoxylin as a routine stain, 

 but that on account of its higher tinctorial power it may have 

 value for some special purposes such as the selective staining of 

 nerve cell bodies of fibrillae and cross striations in muscle cells. It 

 has never been made available commercially, and at present there 

 does not seem to be suflBcient demand for it to justify its production. 



