68 OTHER ANILIN STAINS. 



it stains some kinds of cytoplasm and some kinds of formed 

 material, especially glandular secretions (sericin, for instance) . 

 But the nuclein elements are invariably stained of a bright 

 green (with the exception of the nuclein of the heads of some 

 spermatozoa), whilst extra-nuclear structures are in general 

 stained in tones of blue or violet. 



The following paragraph, translated from the paper by Calberla above 

 quoted, appeared inadvertently without comment in the first edition, and has 

 since been repeated without comment in several places.* 



" He then found that ' the nuclei of subcutaneous connective tissue and 

 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. 



Besides being a perfectly pure chromatin stain, methyl 

 green has other advantages. Staining is instantaneous ; over- 

 staining 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 solu- 

 tion of Bipart 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 

 should be acidulated with acetic acid. 



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

 factorily 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 aqueous media 

 the most fortunate only survive for a few months. 



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. 



Undoubtedly, methyl green is one of the most valuable 



* 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. 



