1 82 ADDENDUM 



Streptococci^, 



" For direct culture the Committee favour the Drigalski and 

 Conradi medium, but only a decidedly impure water would 

 contain streptococci in the maximum amount (i c.c.) which can 

 be spread over a plate. Hence for direct cultures concentration 

 methods appear to be necessary. 



"As regards indirect liquid cultures, glucose formate peptone 

 broth is a suitable medium incubated anaerobically. If it be 

 merely desired to determine the presence or absence of strepto- 

 cocci, microscopic examination of the sediment will suffice, but 

 the Committee recommend the isolation and study of the 

 streptococci by secondary cultures on Drigalski's and Conradi's 

 medium. 



"The Committee consider that it is convenient to exclude all 

 streptococci which do not yield acid in a lactose medium, 

 because the great majority of human faecal streptococci attack 

 lactose, and streptococci of little or no * water significance ' are 

 excluded in this manner. 



" The Committee are of opinion that a water should not be 

 condemned on the streptococcus test alone, if the B. coli and 

 other results are quite satisfactory." 



Standards. The Committee did not go into this difficult 

 question in detail, but reported as follows : 



" The Committee do not think it is practicable to lay down 

 any fixed standards to govern all cases. Speaking generally, the 

 Committee consider that too much stress should not be laid on 

 the number of microbes present in a water, unless the B. coli 

 tests yield confirmatory results. 



" A good water should not contain any B. coli in 100 c.c., 

 but a water containing B. coli in 100 c.c. should not necessarily 

 be objected to without the examination of further samples. 



" Experience has shown that even initially impure waters 



1 Although the writer signed the report as a member of the Committee it should 

 be added, to prevent misunderstanding, that the method for the enumeration of 

 streptococci in water described in the text (page 37) which is not included by the 

 Committee in their recommendations is still considered by him as by far the most 

 suitable and valuable for routine work. 



