BIOLOGY OF CLOSTRIDIUM WELCHII 411 



Simonds was unable to produce toxin in artificial media. 

 Cultures from a normal stool were studied and proved very- 

 pathogenic for guinea-pigs but no evidence of toxin production 

 was shown. He believed that the products of the bacteria, and 

 those of other bacteria present, damaged or killed more tissue 

 and thus spread the infection. Living tissue was not damaged, 

 but in order that growth might occur a sufficiently anaerobic 

 condition must be supplied by the dead tissue. 



Westenhoffer claims that Clostridium Welchii is a pure sapro- 

 phyte and produces its effects in dead tissue only. For its 

 occurrence unfavorable conditions in the tissues are essential. 



Researches by Bull and Pritchett in April and November 1917 

 have completely overthrown all the conceptions previously held 

 of the manner of the pathogenic action of this organism. Experi- 

 ments recently performed by them seem to render all the above 

 theories untenable and to establish the fact that the local destruc- 

 tion of tissues and the lethal effects of Clostridium Welchii are 

 due to a specific bacterial toxin and not to a blood invasion of 

 the micro-organisms nor to acid intoxication. The work shows 

 definitely that under suitable cultural conditions (broth plus 

 sterile non-denatured muscle and +0.1 per cent glucose incu- 

 bated less than twenty-four hours) Clostridium Welchii produces 

 a soluble toxin which after separation from the bacilli, is capable 

 of causing the characteristic lesions and possesses the physical 

 and biological properties of an exotoxin. Furthermore, infec- 

 tions can be successfully prevented and controlled by neutralizing 

 the toxin with a specific immune serum as proved by these 

 writers. 



2. Experimental. The present investigation on pathogenicity 

 is an attempt to differentiate between the human and bovine 

 types and also to present evidence which will substantiate the 

 claims of Bull and Pritchett that the local infection and lethal 

 effects of Clostridium Welchii are due to a specific bacterial toxin 

 which can be neutralized with a specific antitoxin. 



The modes of inoculation by which the pathogenic properties 

 were demonstrated for Clostridium Welchii were subcutaneous, 

 intraperitoneal and intravenous injections of fresh cultures. The 



