BACTERIA IN MILK AND FOOD 251 



Potato. Growth wrinkled and many-folded, gray changing 

 to brown, extending over the entire surface as a thick cover- 

 ing or skin. 



A gar Stroke. Abundant, grayish, fatty, later on wrinkled 

 skin. 



Gelatin Stab. On surface, grayish, fatty exudate covered 

 with skin which slowly sinks as the media liquefy. Gelatin 

 liquefied. No gas in sugar bouillon; acid is formed; no 

 indol. Has been found in ropy or gelatinous bread and is 

 considered the cause. 



Bacillus Butyricus (Hiippe). This bacillus causes bu- 

 tyric-acid fermentation. Supposed to 

 be identical with Bacillus mesentericus. 



Bacillus Amylobacter (Van Tieg- 

 ham) . Synonyms. Clostridium butyri- 

 cum (Prasmowsky) ; Vibrion butyrique of 

 Pasteur; Bacterium saccharobutyricus 

 (Klecki) (Fig. 118). Origin. Found in 

 putrefying plant-infusions, in fossils and 

 conifera of the coal period, in cheese, 

 w r ater, earth. 



Form. Large, thick rods, with 



rounded ends, often found in chains. ,-,. 



> Fig. 118. Bacillus 



A large glancing spore at one end, the amylobacter. 



bacillus becoming spindle shaped in or- 

 der to allow the spore to grow; hence the name, clostridium. 



Properties. Very motile; gases arise with butyric smell. 

 In solutions of sugars, lactates, and cellulose-containing 

 plants and vegetables it gives rise to decompositions in 

 which butyric acid is often formed. Casein is also dissolved. 



A watery solution of iodin will give the starch reaction 

 and color blue some portions of the bacillus; therefore 

 it has been called amylobacter. 



Growth in Glucose A gar. Rapid at 37. Small indefinite 

 colonies with gas-bubbles. No growth in gelatin. 



Bacillus Cyanogenes (Bacterium Syncyanum) (Hiippe). 

 Origin. Found in blue milk. 



