AN AEROBIC SPORE-FORMING BACILLUS 13 



Limiting hydrogen-iron concentrations. Clark's glucose pep- 

 tone-phosphate medium was used after being adjusted with 

 NaOH or HCl to various hydrogen-ion concentrations. Growth 

 between Ph = 5.0 to Pg = 9.0 inclusive. In tube Ph = 

 9.0 very scanty growth and only bubble of gas. In all other 

 tubes much gas, and growth luxuriant. 



Indol production in 1 per cent peptone, four days at 37°C. 

 No indol detected when tested for by the nitrite and by Ehrlich's 

 para-dimethyl-amido-benzaldehyde method. 



Reduction of nitrates. In 0.1 per cent peptone + 0.02 per 

 cent NaNOa solution, four days at 37°C., no reduction to nitrites. 



Litmus milk at 37°C. In twenty-four hours acid, in forty- 

 eight hours partially reduced, coagulated with extrusion of 

 whey, beginning digestion of curd. 



Lactase bile at S7°C. Ninety-six hours, no gas or grov/th. 



Chromogenesis. None noted on any media used. 



OCCURRENCE AND SIGNIFICANCE 



Dr. J. S. Bolten, working in this laboratory, isolated what the 

 writer believes to have been the same or a similar organism from 

 a sample of sewage which had been taken from Mill Creek during 

 the winter of 1916 and stored for forty-one days. Reference to 

 his unpublished notes which are on file at this station, shows that 

 the organism had morphological and cultural characteristics 

 similar to those detailed above. Owing to rather variable and 

 uncertain heat resistance experiments, which Dr. Bolten deemed 

 inconclusive, he was unable to state definitely that the spore- 

 bearer was the gas-former. However, Dr. Bolten used for 

 seeding material in the heat resistance experiments, cultures in 

 lactose broth, in which medium, sporulation is indefinite and 

 delayed. 



Regular examinations are made in this laboratory of samples 

 of water from various sources. These include the Ohio River 

 and its tributaries in the vicinity of Cincinnati, and the tap 

 supplies of Cincinnati and two Kentucky cities on the Ohio 

 River opposite this city. The organism herein described has 



