CHAPTER XIII 



THE INTESTINAL GROUP 



This chapter is devoted to the study of the "intestinal 

 group" of organisms. This collective group may 

 conveniently be subdivided into four subgroups: 



Subgroup I : the colon group. — This group includes 

 different varieties of Bacillus coli, B. lactis aerogenes, and 

 some species of B. acidi lactici. 



Subgroup 2: the hog-cholera, B. enteriiidis, or inter- 

 mediate group. — This group includes B. cholerae suis, B. 

 paratyphosus (several varieties), B. enteritidis, and B. 

 icteroides. The term " intermediate " is assigned to this 

 group, because it resembles the colon group on the one 

 hand, and the typhoid group on the other. 



Subgroup 3: the typhoid-dysentery group. — This 

 group includes B. typhosus, varieties of B. dysenteriae, 

 and B. jaecalis alcaligenes. 



Subgroup 4: the proteus group. — This group includes 

 all varieties of proteus (Bad. termo) and B. cloacae. 



EXERCISE I. STUDY OF SUBGROUP I : THE COLON GROUP 



Inoculate agar-slants from stock-cultures of B. coli 

 (two varieties) and B. lactis aerogenes. Also inoculate 

 one tube of broth with B. coli. 



These two types of B. coli are differentiated by their 

 ability to ferment carbohydrates: 



A. Those which ferment dextrose, lactose, and 

 saccharose. 



B. Those which ferment dextrose and lactose, but 

 not saccharose. 



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