296 YELLOW FEVER; BUBONIC PLAGUE: INFLUENZA. 



in pairs or in short chains of three or four members (Fig. 

 132). Long chains are occasionally seen in very old cult- 

 ures. The organism does not form spores, is not motile, and 

 has no flagella. 



The anilin dyes stain only after a very long exposure of 

 the film to the stain. When stained with Loeffler's alkaline 

 methylene-blue, polar granules can be made out in some of 

 the organisms. Certain it is that Bacillus influenzas stains 



FIG. 132. 



Influenza bacilli. X 1100. (Park.) 



more heavily at its ends than in the middle. Gram's stain 

 decolorizes the germ. Czenzynke's stain is the best for stain- 

 ing the bacillus in blood-films. It is made as follows : 



Concentrated aqueous solution 



of methylene-blue, 40 parts ; 



Solution of eosin (0.5 per cent.) 



in 70 per cent, alcohol, 20 " 



Distilled water, 40 " 



The preparation is placed in this solution for from three to 

 six hours, and is then well washed in water, dried, and 

 mounted in balsam. The red corpuscles are stained red, the 



