OTHER INTESTINAL BACTERIA 211 



The Anaerobic Spore-forming Bacilli. The English 

 bacteriologists have ascribed much importance as 

 indicators of sewage pollution to another group of organ- 

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

 form described as B. aerogenes capsulatus (Welch 

 and Nuttall, 1892) and now called B. welchii, and the 

 form isolated by Klein (Klein, 1898; Klein, 1899) in 

 1895 in the course of an epidemic of diarrhoea at St. 

 Bartholomew's Hospital, described under the name of 

 B. enteritidis sporogenes (now called B. sporogenes) 

 are types. 



The procedure originally described by Klein for 

 isolating B. sporogenes is as follows: a portion of the 

 sample to be examined is added to a tube of sterile 

 milk, which is then heated to 80 C. for 10 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 down 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 18 to 36 hours at 37 the appearance 

 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 



