174 BACTERIOLOGY 



after which it is again rinsed in water and finally mounted 

 for examination. If the decolorization in the acid alcohol 

 be not carried too far, the preparation will show the spores 

 stained blue and the bodies of the cells to have taken on 

 the rose color characteristic of eosin. 



By another process the cover-slip is floated, bacteria 

 down, upon the surface of freshly prepared Koch-Ehrlich 

 solution of fuchsin contained in a watch-crystal. This is 

 then held by its edge with forceps and moved up and down 

 over a small Bunsen flame until the fluid boils gently. This 

 is continued for 2 or 3 minutes. When the fluid has stood 

 for about five minutes after boiling the preparation is trans- 

 ferred, without washing in water, to a second watch-crystal 

 containing the following decolorizing solution : 



Absolute alcohol 100 c.c. 



Hydrochloric acid 3 c.c. 



In this solution it is placed, bacteria up, and the vessel is 

 tilted from side to side for about one minute. It is then 

 removed, washed in water, and stained with the cold 

 methylene-blue solution. The spores will be stained red 

 and the body of the cells blue. 



It must be remembered that there are conspicuous dif- 

 ferences in the behavior of spores of different bacteria to 

 staining-methods and of the spores of a single species in 

 different stages of development. Some stain readily by either 

 of the methods especially devised for this purpose, while 

 others can hardly be stained at all, or only with the greatest 

 difficulty, by any of the known processes; some stain 

 readily when fully developed, but with difficulty when 

 only partly developed; others have this peculiarity reversed. 



Loffler's Method for Staining Flagella. For the demon- 

 stration of the locomotive apparatus possessed by motile 



