PUTREFACTIVE ORGANISMS IO/ 



Potato. A yellowish-brown growth with puckered elevated 

 outline. 



Bouillon. The whole liquid is soon turbid and a dense 

 sediment is deposited. In peptone water indole is produced and 

 much sulphuretted hydrogen gas. 



Milk is rendered acid at 37 C. and coagulated in less than 

 seven days, the curd containing more or less gas. 



Sugar. Grape sugar and lactose are fermented with the pro- 

 duction of acids and much gas, about one-third of which is carbon 

 dioxide, the rest hydrogen and nitrogen. It ferments dulcite also, 

 but most forms do not attack saccharose. A variety which 

 ferments and produces gas from the latter sugar is known as 

 Bact. colt communior. 



4. Associated with Bact. coli in the alimentary canal of many 

 animals is Bacterium lactis aerogenes or Bacterium aerogenes, 

 Escherich, which was first isolated from the small intestine and 

 faeces of infants fed on cows' milk. It is found throughout the 

 intestinal tract and in the stomach, while Bact. coli is chiefly 

 confined to the colon and rectum. 



Typical Bact. aerogenes is a short, thick bacterium very 

 similar in form and dimensions to Bact. coli, usually i to 2 ^ 

 long and .5 /& broad, though much longer cells are not 

 uncommon : it is Gram negative. 



Like Bact. coli it does not form spores, and is a non- 

 liquefier ; it is, however, never motile at any stage of its 

 development. 



Gelatine. On gelatine the surface colonies are rounder in 

 outline, opaque, porcelain - white and convex. The deep 

 colonies are greyish-brown and granular. 



Agar. Thick white shining colonies. 



Potato. Whitish or yellowish brown growth, with elevated 

 warty edges and cheesy odour. 



Bouillon. Turbid, with much sediment, and usually a pellicle 

 or scum on the surface. It forms indole. 



Milk. Milk soon becomes strongly acid, and is coagulated, 



