OTHER INTESTINAL BACTERIA 209 



pollution, a task in which all other tests have so far 

 failed. Unlike the colon bacilli, streptococci from the 

 intestines of cattle and men appear to belong to dis- 

 tinct types. The recognition of- this fact we owe 

 primarily to Gordon (1905), who made an elaborate 

 study of the fermentative power of the streptococci 

 in a long series of carbohydrate media. His work 

 and that of Houston (Houston, 1904; Houston, 1905*, 

 Houston, i905 b ) have made it clear that the streptococci 

 of the herbivora differ from those found in the 

 human body in their low fermentative power. In their 

 review of the genus, Andrewes and Horder (1906) 

 describe the type characteristic of the herbivora under 

 the name, Str. equinus, and define it by its failure to 

 ferment lactose, raffinose, inulin or mannite, or to 

 reduce neutral red. Five other types are described 

 from the human mouth and intestine; all of them 

 ferment lactose, and most reduce neutral red and fer- 

 ment raffinose. The commonest intestinal form clots 

 milk, reduces neutral red and ferments saccharose, 

 salicin, coniferin and mannite. The specific types 

 of the genus Streptococcus, grade into each other by 

 almost imperceptible degrees, and streptococci ferment- 

 ing lactose and raffinose and reducing neutral red are 

 sometimes found in bovine faeces; but the studies made 

 in this country by Winslow and Palmer (1910) confirm 

 the conclusions of the English observers that there are 

 specific differences between the streptococci of the 

 human, bovine, and equine intestines. The most im- 

 portant of these results are indicated in the table 

 below: 



