METHYL GREEN AND EOSIN. 163 



possesses the usual qualities of mixtures of Methyl Green and 

 Acid Fuchsin, the Orange apparently coming into play only 

 in special cases. The stain works well, and may be put into 

 the hands of beginners. It is on the whole an excellent 

 formula, and will give valuable results in many cases, but 

 possesses no special magic, and is not likely to supersede 

 those amongst other staining methods that extended experi- 

 ence has found to be valuable. It may not be amiss here to 

 repeat the warning that there neither is nor can be such a 

 thing as a universal reagent in histology " nouvel objet, 

 nouvelle methode !" 



Gilson adds that for cytological purposes the proportions 

 of the ingredients should be varied according to circumstances. 

 For cells whose nuclein is less chromophilous than the aver- 

 age, the proportion of methyl green should be increased, and 

 in the opposite case the proportion of acid fuchsin should be 

 increased. 



For the special purpose of obtaining a minutely precise stain of attraction 

 spheres and other cytoplasmic elements, HEIDENHAIN recommends that the 

 mixture be acidified. For the somewhat minute details of the process and 

 of the results, see 639 in " Cytological Methods " in Part II. 



The stain will work with chrome-osmium mixtures, but I 

 believe does not give so fine a coloration with them as with 

 sublimate. 



Dr. LINDSAY JOHNSON writes me, " For nerve tissues, brain 

 and cord, retina and cochlea, &c., nothing in my opinion can 

 beat the Ehrlich-Biondi stain to which about one third of 

 twenty per cent, (saturated) solution of nigrosin is added " 

 (see the paragraphs on " Retina " in Part II) . Dr. Johnson also 

 points out that it has the advantage of giving a stain whose 

 colours are photographically correct ; he says " it is the stain 

 par excellence for photography, except where there are fibrous 

 or cartilaginous tissues, which it stains red." 



I cannot say to what extent the stain is permanent. 

 Heidenhain says that the preparations made according to his 

 acid method mentioned above are absolutely permanent. 



260. Methyl Green and Eosin (CALBEELA, Morph. Jahrb., iii, 1877, 

 Heft 3, p. 625). Mix 1 part of eosin with 60 parts of methyl green, and 

 dissolve the mixture in warm 30 per cent, alcohol. 



Sections stain in this solution in five or ten minutes; they should be 

 quickly washed in successive alcohols, and mounted in balsam or glycerin. 



