320 BACTERIOLOGY. 



METHOD OF STAINING THE BACILLUS OF BUTYRIC 

 ACID FERMENTATION. 



Treat the bacilli with iodine-solution. At certain stages 

 of the fermentation-process the plasma takes" a blue or 

 violet-black coloration. The young rods give the former 

 appearance, and the older ones the latter. It is most 

 easily observed when the bacillus is cultivated in a sub- 

 stance containing starch, or, if starch is wanting, in the 

 presence of cellulose, calcium-lactate, or glycerine; in 

 bacilli cultivated in sugar solutions the reaction seldom 

 appears. 



Clostridium polymyxa, Prazmowski. Threads 

 consisting of rods which vary in length ; cocci, 

 involution-forms, and spores are also present ; cul- 

 tivated on nourishing solutions they develop a thick 

 skin on the surface. On boiled beet and other 

 roots they form a gelatinous scum, which often 

 consists of crinkled, tough masses, several cm. in 

 diam., somewhat similar to the Ascococcus Bitlrothii. 

 They cause fermentation in solutions of dextrine, 

 and more actively in potato or bean paste. Some 

 cells give the iodine reaction weakly, as in Clostri- 

 dium butyricum. 



Clostridium of symptomatic anthrax (Ramch- 

 brand, Charbon symptomatique.*} Rods rounded at 

 the ends, mostly with a shining spore at one end. 

 They are especially distinguished from the bacilli 

 of anthrax by being motile. Cultivated on blood- 



* Arloing, Cornevin et Thomas, Bull, de V Acad. de Med. 1881. 



