PUTREFACTIVE ORGANISMS ill 



each coccus being about i p in diameter, and readily stains by 

 Gram's method. It is a facultative anaerobe, and grows very 

 slowly at 20 C., the optimum temperature being 37 C. The 

 colonies on gelatine and agar are always very small, round, and 

 white or yellowish white, almost flat, and do not liquefy the 

 medium. On potato there is little or no growth. Milk is 

 generally coagulated in twenty-four hours or less, and glucose 

 bouillon becomes acid without separation of gas. A great 

 many allied forms or species are known, differing chiefly in 

 length of " chains " and in pathological virulence. 



(3) Micrococcus flavus is a coccus .5 to i ^ in diameter, 

 occurring usually in pairs, or three or four together. It is an 

 aerobic species, which grows well at 20 C. The gelatine colonies 

 are small, round, yellowish-white ; they liquefy and sink into the 

 medium. The liquefied gelatine stab is funnel-shaped, with 

 yellowish sediment. On potato its growth is distinct, thin, and 

 yellowish or greenish yellow. Milk is only partially coagulated, 

 and rendered acid in two or three weeks. This species is said 

 to be identical with or closely allied to Sarcina hitea, Fliigge, 

 but typical sarcina " packets " are not formed. 



9. The spore-producing species, Bs. subtilis (page 124) and 

 Bs. vulgatus (page 126), are not uncommon bacteria in decaying 

 organic matter. 



10. The organisms already described are those chiefly found 

 in the early stages of the putrefactive process, when there is 

 abundant access of air. The production, however, of some of 

 the most characteristic foul-smelling substances in decomposing 

 materials is dependent upon anaerobic conditions, and bacteria, 

 which carry on their work best in the absence of oxygen, are 

 always present in putrefying substances. In fact, the proteins 

 of organic matter appear to be more rapidly and more 

 effectually broken down by anaerobic species than by the 

 aerobes. 



The chief of these anaerobes is Bacillus putrificus, Bienstock, 

 which is found in dung and sewage, and is very common in 



