BIOLOGY OF CLOSTRIDIUM WELCHII 391 



fermentative and whose putrefactive functions are very slight 

 or absent." 



S. Enzymes. Enzyme action is shown in the liquefaction of 

 gelatin and blood serum and the peptonization of milk casein. 

 Diastatic enzymes may be detected by growing cultures of 

 Clostridium Welchii in starch solution when the starch is con- 

 verted into sugars. 



IX. CLASSIFICATION 



1. Historical. The success that has attended previous in- 

 vestigators in the use of certain carbohydrates and other fer- 

 mentable substances as a means of differentiating between the 

 different members of a group suggested the use of these substances 

 as a means of distinguishing members of the Clostridium Welchii 

 group. 



Little has been accomplished in the separation of the members 

 of this group due presumably to the fact that the differences are 

 so small and that it has been impossible to obtain uniform 

 conditions. 



Fraenkel, 1902, and Klein, 1900-1902, recognized only one 

 variety of the organisms isolated by them. Schattenfroh and 

 Grassberger, 1900, and Passini, 1905, differentiated two species, 

 virulent and non-virulent. Hitschmann and Lindenthal, 1899, 

 were unable, either from the behavior in the animal body or 

 in cultures, to differentiate varieties. They found tests of 

 pathogenicity especially unreliable as a means of differentiation. 

 Passini, 1904, Werner, 1905, and Rocchi, 1911, by means of 

 serological reactions attempted to distinguish subvarieties but 

 failed. Herter, 1907, was also unsuccessful in his attempt to 

 apply such factors as sporulation, pathogenicity, hemolytic 

 properties, indol production and rapidity of gas formation in 

 man and animals. 



Jackson, 1912, described two types, one motile, neutral reaction 

 with no gas formation in lactose bile and 56 per cent gas pro- 

 duction in mannitol broth; the other non-motile, 92 per cent 

 gas production in lactose bile and 10 per cent gas production in 

 mannitol broth. 



