INFLAMMATION. 143 



tococcus, colon bacillus, Bacillus pyocyaneus) , 

 which in the same locality in the adult appear 

 harmless. The fact that many individuals are not 

 stricken in an epidemic, in which all are equally 

 exposed to infection, points to the probability that 

 pathogenic organisms (typhoid, cholera and dys- 

 entery) often traverse the intestinal canal without 

 inducing disease. Naturally, microbes are elimi- 

 nated in enormous quantities in the feces, and in 

 inflammatory states this elimination is increased 

 by diarrhea. It is also not to be forgotten that the 

 intestinal tract is, to a considerable extent, a 

 lymph oid organ, and that in the presence of infec- 

 tion enormous quantities of phagocytes can be 

 called into action quickly. 



The protective properties of the genito-urinary 

 surfaces are not different in principle from those 

 already mentioned (vaginal acidity, mechanical 

 and perhaps bactericidal cleansing by the men- 

 strual flow, urinary irrigation). 



(2) Internal Protective Agencies. 

 A. Inflammation. 



Although there are many chemical and physical 

 agents which may cause inflammation, we are in- 

 terested here only in those of an infectious na- 

 ture. 



Inflammation may be considered as a reactive Nature of 

 condition on the part of the tissues, which devel- l 

 ops in response to the action of some injurious 

 agent. The process may be beneficial in some in- 

 stances, while in others it may be pernicious from 

 the beginning to the end. The thickening of the 

 endothelium of the cerebral vessels as one sees it 

 in syphilis is a progressive, reactive change which 



