NON-PATHOGENIC BACILLI. 



689 



spores are destroyed by a temperature of 100 C. maintained for five minutes. 

 In solutions containing- starch, sugar, dextrin, or salts of lactic acid this ba- 

 cillus produces a considerable quantity of butyric acid, and at the same time 

 carbon dioxide and hydrogen are given off. The most favorable tempera- 

 ture for its development is from 35 J to 40 C. According to Fitz, it does not 

 cause the coagulation of sterilized milk, but the casein is slowly peptonized. 

 This bacillus also causes the decomposition of cellulose, producing hydrogen 

 and carbon dioxide, or methane, carbon dioxide, and sulphuretted hydrogen, 

 according to the composition of the culture medium (Tappeiner). It appears 

 to be the bacillus which usually gives rise to butyric acid fermentation in 

 milk which has been kept for some time, and also in cheese ; this occurs in 

 milk after the lactic acid fermentation, which is due to aerobic bacilli, and 

 especially to Bacillus acidi lactici. The characters of growth in solid media 

 have not been determined. A peculiar staining reaction occurs when this 



D 



FIG. 231. Bacillus butyricus; A, single bacilli; B, chains and filament; C, spore formation, 

 showing " clostridium form " ; D, germination of a spore a to i. X 1,020. (Prazmowski.) 



bacillus from cultures containing starch or cellulose is treated with iodine 

 solution ; the protoplasm of the cells acquires a blue or dark-violet color, the 

 younger cells being of a pure blue ; in some cases an oblique zone of blue 

 only is seen, in others the entire cell is stained. 



405. CLOSTRIDIUM FCETIDUM (Liborius). 



Obtained from garden earth by inoculations in mice, etc. 



Morphology. Bacilli of various lengths and about 1 u thick ; sometimes 

 grow out into filaments. Forms large oval spores, located centrally or at 

 one end of the rod ; these are of greater diameter than the bacilli before spore 

 formation, and cause the rods to have a spindle (clostridium) form, or oc- 

 casionally an expanded extremity ; resembles Bacillus butyricus. 



Biological Characters. An anaerobic, liquefying, actively motile ba- 

 cillus. Forms spores. Grows in the usual culture media, in the absence of 



