STAINING REAGENTS. 33 



Brown with Bismarck brown, vesuvin, and chrysoidin. 

 Green with methyl green. 



Blue or violet with haematoxyhn, methyl blue, methyl violet, 

 dahlia, gentian violet, &c. 

 The first experiments on staining germs were made with carmine 

 and haematoxyhn, and Koch and others were successful in staining 

 not only the bodies of bacteria, but also, in certain cases, in demon- 

 strating the flagella. These reagents are now, however, superseded 

 by the aniline colours, principally the basic series (though these will 

 not stain flagella of bacteria as well as a concentrated aqueous extract 

 of logwood, the specimen being afterwards treated with a solution 

 of chromic acid). 



Weigert's gentian violet and picro-carmine method demonstrates 





■■f Ar '-^^ 



■^ <' 



tf 





Fig. 3. — Blood taken from a case of traumatic tetanus. Blood 

 corpuscles and micro-organisms stained with methyl violet, mounted 

 in Canada balsam. { x 700.) 



most admirably the affinity of the basic aniline colours. The sections 

 are first placed in gentian violet (§ 27, p. 40), then washed in alcohol, 



c 



