METHYL GREEN. 75 



those of vessels and nerve-sheaths stained rose-red, cells of the coriuni 

 reddish white, and the cells of epidermis greenish blue to pure blue.' " 



It should have been added that Calberla here says what he presumably 

 did not mean to say. Methyl green certainly never stains nuclei red, and 

 Calberla's observation should be taken to . refer to the results of a double 

 stain with methyl green and eosin, which is mentioned in the somewhat ob- 

 scurely expressed passage from which the quotation is taken. 



Calberla's misstatement is repeated, and made one of the grounds of an 

 important theoretical deduction by Griesbach, in Zeit. f. wiss. Mik., iii, 3, 

 1886, p. 365. 



Besides being a perfectly pure chromatin stain, methyl 

 green has other advantages. Staining is instantaneous ; 

 overstaining never occurs. The solution is very penetrating, 

 kills cells instantly without swelling or other change of form, 

 and preserves their forms for at least some hours, so that it 

 may be considered as a delicate fixative. Osmic acid (0*1 to 

 1 per cent.) may be added to it, or it may be combined with 

 solution of KIPART and PETIT (this, by the way, is an excellent 

 medium for washing out in and mounting in) . 



Alcoholic solutions may also be used for staining. They 

 also should be acidulated with acetic acid. 



The stain does not keep easily. It is difficult to mount it 

 satisfactorily in balsam, because the colour does not resist 

 alcohol (unless this be sufficiently charged with the colour) ; 

 and of preparations mounted with excess of colour in the 

 usual aqueous media the most fortunate only survive for a 

 few months. Dr. HENNEGUY however writes to me that it 

 keeps well in BRUN'S glucose medium (see 402). 



It was first pointed out, I believe, by Heschl (Wiener med. Wochenschr., 

 2, 1879), that methyl green is a reagent for amyloid degeneration. His 

 observations were confirmed by Curschmann (Virchow's Arch., t. 79, 1880, 

 p. 556), who showed that it colours amyloid substance of an intense violet, 

 but this (as pointed out by SQUIBE, Methods and Formulas, &c., Churchill, 

 1892, p. 37) may be due to its containing methyl violet as an impurity. 



Undoubtedly methyl green is one of the most valuable 

 stains yet known. It is the classical nuclein stain for fresh 

 tissues. 



110. Bismarck Brown (Manchester Brown, Phenylen Brown, 

 Vesuvin, La Phenicienne) . A fairly pure nuclear stain that 

 will work either with fresh tissues or with such as have been 

 hardened in chromic acid. 



