BIOLOGY OF CLOSTRIDIUM WELCHII 415 



were performed on guinea-pigs by injecting the heated spores 

 subcutaneously in 1 and 5 cc. quantities. In each case the ani- 

 mals increased in weight and showed no apparent reaction. The 

 fifth experiment was an intravenous injection of 10 cc. of a spore 

 culture from human feces in a rabbit weighing 2200 grams with 

 negative results. 



From these results it is safe to assume that spores heated to 

 80° for fifteen minutes do not readily germinate in the circulation 

 or in living tissue. Apparently when spores of Clostridium 

 Welchii gain entrance to living tissue, they adapt themselves to 

 the amount of oxygen present to such a degree that they will 

 survive for a time but do not produce infection. Thus the 

 healthy human body is protected against infection by the spores 

 of Clostridium Welchii which are so widely distributed. In the 

 case of injury to the tissues such as wounds, fractures, etc., 

 there is a sufficient anaerobic condition in the dead tissue to allow 

 the organism carried into the wound to begin to grow and produce 

 its characteristic lesions. 



Previous to the investigations of Bull and Pritchett, 1917, 

 no explanation could be given for the fact that spores would 

 not germinate and produce fatal results. When vegetative forms 

 were injected in sufficient quantities in living tissue, inflammation 

 and necrosis of the subcutaneous tissues and muscles developed 

 causing death but no reason could be found for the behavior 

 of spores. Bull and Pritchett, 1917, determined the fact that 

 the toxicity of the fluid is destroyed by heating for 30 minutes 

 at 70° and is greatly diminished at 62° for a similar period. 

 Therefore, it is probable that the toxin was destroyed by heat 

 in these experiments on the effect of the inoculation of spores 

 and hence no necrosis or local lesions were produced. This 

 fact strengthens the view that a toxin is produced during the 

 growth of the bacillus. 



8. Effect of acid upon the tissues. The following experiments 

 were conducted to determine whether or not the presence of 

 acid in the culture has any effect upon pathogenicity. Cultures 

 grown for eight to ten hours were injected in most cases, while 

 in a few cases twenty-four hour cultures were used. The acidity 



