CHAPTER III. 

 INFECTION AND INTOXICATION. 



ZiEGLER defines infection as " the entrance of bacteria 

 into the body and their increase there." In the majority 

 of cases it means the entrance into and multiplication of 

 bacteria in the tissues, though this cannot be given as a 

 definition because of the possibility that certain bacteria, 

 as, for instance, the cholera organisms, may begin their 

 pathogenic effects by poisonous action upon the mucous 

 membrane of the intestine before they succeed in enter- 

 ing the tissues. While it may be true of a few infectious 

 bacteria that entrance into the tissues is unessential for 

 their pathogenesis, it is also true that some of the cavi- 

 ties of the body contain bacteria which flourish in their 

 fluids and cause no departure from normal conditions. 

 When abnormal conditions arise, however, and enable 

 them to leave their normal habitat, they may become the 

 cause of serious ills. This is particularly the case with 

 the intestine. Under normal conditions the colon bacil- 

 lus and the streptococcus are pretty constant inhabitants 

 of the entire tract, living a saprophytic existence upon 

 the contained fecal matter. Should a portion of the 

 intestinal wall become ulcerated or strangulated, these 

 usually harmless bacteria penetrate into the tissues, some- 

 times causing local, sometimes metastatic suppurative 

 affections. 



The time at which infection takes place varies some- 

 what according to the kind of bacterium with which we 

 have to deal. Thus, in the case of some whose early 

 operations are obscure, as typhoid and cholera germs, 

 infection occurs at the moment at which the bacteria 

 enter the alimentary canal. In the case of the colon 



62 



