ENTRANCE AND SPREAD OF BACTERIA 187 



that from time to time a certain number of such organisms gain 

 entrance to it from trifling lesions of the skin or mucous surfaces, 

 the possibilities of entrance from the latter being especially 

 numerous. In most cases they are killed by the action of the 

 "healthy serum or cells of the body, and no harm results. If, 

 however, there be a local weakness, they may settle in that part 



FIG. 60. Secondary infection of a glomerulus of kidney by the staphylo- 



coccus aureus, in a case of ulcerative endocarditis. The cocci (stained 



darkly) are seen plugging the capillaries and also lying free. The 



glomerulus is much swollen, infiltrated by leucocytes, and partly necrosed. 



Paraffin section ; stained by Gram's method and Bismarck-brown. x 300. 



and produce suppuration, and from this other parts of the body 

 may be infected. Such a supposition as this is necessary to 

 explain many inflammatory and suppurative conditions met with 

 clinically. In some cases of multiple suppurations due to 

 staphylococcus infection, which we have had the opportunity to 

 examine, only an apparently unimportant surface lesion was 

 present ; whilst in others no lesion could be found to explain 

 the origin of the infection. The term cryptogenetic has been 

 applied by some writers to such cases in which the original 



