42 MANUAL OF BACTERIOLOGY. 



the same as far as the bacteria are concerned; fibrin and hyaline 

 material are stained blue, bacteria violet. It is often impossible 

 to decolorize the nuclei completely without decolorizing the 

 bacteria also. The parts of the nuclei which remain stained 

 often present pictures that resemble bacteria, and which may 

 lead to error if not recognized. Basophilic granules also retain 

 the stain, as do the horny cells of the epidermis. These re- 

 marks apply also to Gram's method, except as regards fibrin. 

 Very beautiful preparations can be obtained according to this 

 or the Gram method when the sections have previously been 

 stained in carmine; the nuclei will then be colored red, bacteria 

 violet. 



Tubercle bacilli may be stained in sections as follows : 



(a) Use carbol-fuchsin, or aniUne-water gentian-violet for 

 one-haK to two hours with very gentle warming, or over night 

 without warming. See page 40 for the manner of handling 

 sections. 



(h) Wash in water. 



(c) Decolorize with some one of the decolorizing agents 

 mentioned in connection with the staining of tubercle bacilli 

 in cover-glass preparations, preferably 3 per cent, hydrochloric 

 acid alcohol. Decolorization must be continued until the red 

 color has disappeared, which requires one-half to several 

 minutes. 



{d) Wash in alcohol. 



(e) Wash in water. 



(/) Use hematoxylin as a contrast-stain for fuchsin prepara- 

 tions, and carmine for gentian-violet preparations. In the latter 

 case it is better to stain with carmine before staining the bacilli. 

 The carmine is not affected by the subsequent treatment. 



{g) Wash in water. 



{h) Alcohol. 



{i) Xylol. 



(/) ^Balsam. 



