THE ANAEROBIC BACILLI 753 



subterminal. B. Welchii is the most active fermenter in the sac- 

 charolytic group. It ferments all the common sugars with the pro- 

 duction of large amounts of gas. Lactic and butyric are the two 

 acids most frequently formed, the latter often giving cultures of 

 B. Welchii a characteristic odor. Glucose agar is sometimes frag- 

 mented to such an extent that the plug is blown off the tube. 

 Simonds 9 has been able to divide the B. Welchii group into sub- 

 divisions depending on the ability to ferment either glycerine or 

 inulin, or both, or neither, and this classification has been confirmed 

 by Henry. 10 In wounds, B. Welchii ferments the muscle sugar 

 producing gas in the tissues and for this reason is commonly called 

 the "gas" bacillus. The crepitation thus produced is characteristic 

 of gas gangrene and indicates the extent of the infection. The rapid 

 fermentation of the lactose in milk gives a characteristic reaction 

 in this medium which is diagnostic for B. Welchii. The acid clot 

 torn by gas bubbles and the separation of the milk into coagulum 

 and whey is easily recognized and is not given by other anaerobes. 

 The inoculation of a mixed culture from a wound into milk makes 

 possible the diagnosis of B. Welchii within twelve to eighteen hours. 



Opinions as to the ability of B. Welchii to liquefy gelatin vary 

 greatly. B. Welchii does not grow well on sugar-free gelatin and 

 it is, therefore, difficult to draw conclusions as to its action on 

 gelatin. B. Welchii as pointed out by Rettger in 1906, 11 never 

 attacks proteins if carbohydrates are present and even in the absence 

 of carbohydrate shows only a very slight proteolytic activity. No 

 indol is formed from broth, and coagulated serum is not liquefied 

 or blackened. 



The hemolytic power and pathogenicity of different strains of 

 B. Welchii vary greatly. B. Welchii is particularly pathogenic for 

 guinea-pigs and pigeons, the latter being used in the standardization 

 of B. Welchii toxin. B. Welchii in fatal cases usually invades the 

 blood stream shortly before death, and can usually be isolated from 

 the blood after death. Spores are never formed in the animal body. 

 Rabbits and mice are much less susceptible. Agglutinin production 

 in response to injections of B. Welchii in rabbits and horses is 

 extremely poor. Simonds obtained a serum in rabbits which agglu- 

 tinated the homologous strain in a dilution of 180. Ten strains 



9 Simonds, Mon. Rock. Inst., No. 5, 1915. 



10 Henry, Jour. Pathol. and Bacter., 21, 1917, -344. 



11 Rettger, Jour. Biol. Chem., 11, 1906, 71. 



