296 WATER HYGIENE 
in water. The evidence, however, is less convincing than that of B. coli 
since it is probable that the methods which exist for differentiating 
between fecal and non-fecal streptococci are unreliable. Their short life 
in water points out that a negative result for their examination may not 
indicate the absence of pollution. More data with regard to the strep- 
tococci as indicators of pollution are needed. Savage and Reed (1916) 
in some work on this subject found that neutral red broth was the best 
medium. They regard the estimation of the streptococci as of un- 
doubted value but that a positive result has much more meaning than a 
negative result. The same author with the collaboration of Wood 
(1917) compared the viability of B. cols and streptococci in natural 
waters. The streptococci were not able to live longer than two weeks 
while B. colt showed a distinct multiplication. Im one instance the 
bacilli increased to fifty times the original number in eleven weeks. 
The presence of the streptococci in a water would indicate recent pollu- 
tion and, therefore, of a more dangerous nature. The greatest objec- 
tion to the use of the streptococci as indicators of pollution is the lack of 
a rapid method for detecting them in a sample of water. Savage has 
recommended the use of neutral red media but this does not exert a 
sufficiently selective action to render the test easily and quickly carried 
out. The author has found that it was necessary to verify the suspected 
streptococci with hanging drop determinations in many of the cases 
where neutral red was used. 
Houston’s Method for Streptococci in the Feces. Drigalski and 
Conradi plates are inoculated from an emulsion of the feces, made in 
sterile water. After incubation at 37° C., the minute colonies are sub- 
cultured in “ litmus lemco, lactose peptone’’ medium. After twenty- 
four hours the tubes showing no acidity are discarded; those showing 
acidity are examined microscopically and if results were satisfactory 
further subcultures were made into a series of lemco peptone sugar 
media untinted with litmus. After three days incubation at 37° C. 
the acidity produced is estimated with N/20 NaOH, using phenol- 
phthalein as the indicator. Control tubes are also inoculated. (Mtr. 
Water Bd. 10th Am. Rept., p. 25, 1914.) 
The streptococcus colonies on Drigalski and Conradi plates are small 
colonies with a tinge of violet. They are to be distinguished from col- 
onies of B. typhosus which possess larger colonies. 
Detection of Sewage Streptococci. ‘“ For this purpose many proc- 
esses have been devised, but the simplest and best appears to be the 
examination of the bile-salt glucose broth used for the ‘ presumptive 
test ’ for colon bacilli. The incubation should, however, be prolonged 
