158 



BACTERIOLOGY. 



of the bottle. The bottles are then to be labelled 

 "saturated alcoholic" or "watery" solution of fuchsin, 

 gentian-violet, or methylene-blue, as the case may be. 

 The alcoholic solutions are not directly employed for 

 staining-purposes. 



The solutions with which staining is accomplished 

 are made from the stock solutions by adding 5 c.c. of 

 the latter to 95 c.c. of distilled water. 



TIG. 88. 



Back of bottles for staining-solutions. 



The above represent the staining-solutions in every- 

 day use. They may be kept in bottles supplied with 

 stoppers and pipettes (Fig. 33), and when used are 

 dropped upon the preparation to be stained. 



For certain bacteria which stain only imperfectly 

 with these simple solutions it is necessary to employ 

 agents that will increase the penetrating action of the 

 dyes. Experience has taught us that this can be accom- 

 plished by the addition to the solutions of small quan- 

 tities of alkaline substances, or by dissolving the staining- 

 materials in strong watery solutions of either aniline or 

 carbolic acid, instead of water in other words, by 

 employing special solvents and mordants with the stains. 



