104 MICROSCOPIC METHODS. 



Blue Stains. Methylene-blue 1 (synonym : phenylene-blue). 

 Victoria-blue. 

 Thionin-blue. 



Red Stains. Basic fuchsin (synonyms : basic rubin, magenta). 

 Safranin (synonyms : fuchsia, Girofle). 



Bro^vn Stain. Bismarck -brown (synonyms : vesuvin, phenylene- 

 brown). 



It is of the greatest importance that the stains used by 

 the bacteriologist should be good, and therefore it is 

 advisable to obtain those prepared by Griibler of Leipzig. 

 One is then perfectly sure that one has got the right 

 stain. 



Of the stains specified, the violets and reds are the most 

 intense in action, especially the former. It is thus easy 

 in using them to overstain a specimen. Of the blues, 

 methylene-blue probably gives the best differentiation of 

 structure, and it is difficult to overstain with it. Thionin- 

 blue also gives good differentiation and does not readily 

 overstain. Its tone is deeper than that of methylene-blue 

 and it approaches the violets in tint. Bismarck-brown is 

 a weak stain, but is useful for some purposes. Formerly 

 it was much used in photomicrographic work, as it was less 

 actinic than the other stains. It is not, however, needed 

 now, on account of the improved sensitiveness of the 

 plates. 



It is most convenient to keep saturated alcoholic solu- 

 tions of the stains made up, and for use to filter a little 

 into about ten times its bulk of distilled water in a watch- 

 glass. A solution of good body is thus obtained. Most 

 bacteria (except those of tubercle, leprosy, and a few others) 

 will stain in a short time in such a fluid. Watery solutions 

 may also be made up, e.g. a saturated watery solution of 

 methylene-blue or a i per cent solution of gentian-violet. 

 Stains must always be filtered before use. Otherwise there 

 may be deposited on the preparation granules which it is 

 impossible to wash off. The violet stains in solution in 



1 This is to be distinguished from methyl-blue, which is a different com- 

 pound. 



