ADDENDUM 



cannot establish its origin, although they do enable deductions 

 as to its origin to be made with some degree of probability. The 

 varying methods of recording make it impracticable to tabulate 

 all the results together and draw general deductions as to their 

 relative grouping. Some special points and conclusions may 

 however be mentioned. 



The results of Stowell, Hilliard and Schlesinger are of con- 

 siderable interest. They studied 240 strains from milk and 

 from the normal human throat using the titration method. 

 They draw attention to the value of testing the fermentation 

 abilities of streptococci at low as well as high temperatures. 

 They suggest that six different tubes of media will differentiate 

 any streptococcus between these two sources, i.e. glucose, 

 lactose, raffinose and salicin at 37 C, and lactose and sac- 

 charose at 20 C. Four of these tests would be considered 

 diagnostic. 



They believe that the following features are sufficient to 

 separate the milk from the throat streptococci. The former yield 

 over 2'5 per cent, acid in lactose and saccharose at 37 C., seldom 

 ferment a substance higher than saccharose in the metabolic 

 series, readily grow at 20 C. in glucose, lactose and saccharose 

 media, while on the other hand the throat streptococci seldom 

 yield over 2*5 per cent, acid in any substance at any tempera- 

 ture, over 40 per cent, yield more than I *2 per cent, of acid in 

 either salicin or raffinose or in both at 37 C. ; at 20 C. they 

 almost never attack any of the test substances. 



Fuller and Armstrong, using the titration method, investi- 

 gated the biological characters of streptococci from animal and 

 human excreta. They found that the streptococci of human 

 faeces were characterised by high acidity in glucose, lactose 

 and mannite, a low acidity in raffinose and a relatively low 

 acidity in glucose, lactose and especially mannite. Many 

 individual variations were however met with. 



Houston has recently re-investigated this question, using the 

 American titration method. He found it very difficult to isolate 

 lactose fermenting streptococci from the lower animals except 

 the dog, whereas the great majority of human faecal streptococci 

 yield streptococci which ferment lactose. He adds " so few 



