Other Intestinal Bacteria. 161 



of organisms, the anaerobic spore-forming bacilli, of which 

 the B. sporogenes is a type. This form was isolated by 

 Klein (Klein, 1898; Klein, 1899) in 1895, in the course 

 of an epidemic of diarrhoea at St. Bartholomew's Hos- 

 pital, and described under the name of B. enteritidis- 

 sporogenes; it is closely related to the B. aerogenes capsu- 

 latus of Welch (Welch and Nuttall, 1892). 



Klein's procedure for isolating the B. sporogenes is 

 simple in the case of highly polluted waters. A portion 

 of the sample to be examined is added to a tube of sterile 

 milk, which is then heated to 80 C. for ten minutes 

 to destroy vegetative cells. The milk is next cooled and 

 incubated under anaerobic conditions, which may be 

 accomplished most conveniently by Wright's method. A 

 tight plug of cotton is forced a quarter way c\own the test 

 tube, the space above is loosely filled with pyrogallic acid, 

 a few drops of a strong solution of caustic potash are 

 added, and the tube is tightly closed with a rubber stopper. 

 After eighteen to thirty-six hours at 37 degrees the appear- 

 ance of the tube will be characteristic if the B. sporogenes 

 is present. "The cream is torn or altogether dissociated 

 by the development of gas, so that the surface of the 

 medium is covered with stringy, pinkish-white masses of 

 coagulated casein, enclosing a number of gas-bubbles. 

 The main portion of the tube formerly occupied by the 

 milk now contains a colorless, thin, watery whey, with a 

 few casein lumps adhering here and there to the sides of 

 the tube. When the tube is opened, the whey has a smell 



