210 ELEMENTS OF WATER BACTERIOLOGY 



COMPARATIVE FERMENTATIVE POWER OF STREPTO- 

 COCCI FROM THE HORSE, THE COW, AND MAN 



(WINSLOW AND PALMER, 1910) 



The rarity of lactose-fermenting streptococci in the 

 horse makes it probable that this group can be used for 

 distinguishing pollution by street washings from that 

 due to domestic sewage; and the fact that a considera- 

 bly larger proportion of human strains attack mannite 

 and a considerably larger proportion of bovine strains 

 ferment raffinose should make it possible to use the 

 ratio between results in these two media to distinguish 

 between the wash from pastures and cultivated land 

 and sewage. Clemesha (i9i2 a ) in India has, however, 

 obtained very different results. Out of 115 strains of 

 streptococci from human faeces 92 per cent belonged 

 to the "lamirasacsal" class of Houston (acid in lactose, 

 clot in milk, acid in raffinose, saccharose and salicin), 

 and none acidified mannite. Of 39 strains from cow 

 dung all belonged either to this same " lamirasacsal " 

 class or to the " larasacsal " class (differing only in 

 failing to clot milk). Nevertheless, in view of the 

 importance of distinguishing between human and animal 

 pollution and the hopelessness of doing so by means 

 of the colon group these different types of streptococci 

 well deserve further study. 



