CONDITIONS OF INFECTION. 411 



that penetrating wounds in which infected ma- 

 terial is carried beneath the fascise, as the rusty 

 nail wounds, also those accompanied by deep lac- 

 erations, as wounds inflicted with blank cartridges, 

 or those in which dirt and micro-organisms have 

 been ground into the tissues, as in crushing inju- 

 ries., are prone to be followed by tetanus. Under 

 such conditions the bacillus lies deeply imbedded 

 in the tissues and remote from the air. 



Of equal importance is the presence of foreign inhibition of 

 matter and particularly of other micro-organisms. 

 Eelatively superficial wounds in which there is 

 laceration of the tissue with consequent necrosis, 

 as in wounds by toy pistols, even the paper-cap 

 pistol, are well adapted for the development of 

 tetanus if the germs were on the skin at the time 

 of injury. Necrotic tissue favors the proliferation 

 of the tetanus bacilli in two ways. In the first 

 place it seals up the wound to a certain extent, 

 and thus provides the requisite anaerobic condi- 

 tion ; in the second place it would seem to prevent 

 phagocytosis of the bacilli in some obscure way. 

 It has been suggested that the strong, chemotactic 

 relation which exists between necrotic material 

 and leucocytes causes the latter to take up the dead 

 tissue rather than the bacilli. That innocent for- 

 eign material may favor the development of teta- 

 nus in the presence of the microbes was shown by 

 Vaillard and Rouget: tetanus would develop in 

 the presence of an artificially produced hematoma 

 or a subcutaneous fracture while in the absence of 

 such predisposing factors the bacilli were taken up 

 by phagocytes. 



Saprophytic organisms and the pus-producing Mixed 



. r .* / ... . Infections. 



cocci which are usually found in wounds contami- 



