238 MANUAL OF BACTERIOLOGY. 



or it may be only the commencement of a large carbuncle 

 with a central slough. Such infection has been produced ex- 

 perimentally on the human skin by rubbing in cultures of 

 Staphylococcus pyogenes aureus. It is, furthermore, the con- 

 stant experience of post-mortem examiners that infection may 

 occur around the hair-follicles when no wound of the skin 

 has been inflicted. 



In many instances, infection with the pyogenic bacteria 

 follows upon some preexisting infection; this happens, for in- 

 stance, in tuberculosis, when tuberculous lungs become in- 

 fected with Streptococcus pyogenes, leading to the formation 

 of a cavity. It is a common occurrence in gonorrhea, after 

 the acute stage of the disease has passed, when we find the 

 gonococcus in the pus, mingled with other pyogenic micro- 

 cocci. Secondary infection with pyogenic bacteria is frequently 

 due to the Streptococcus pyogenes, often also to the Micro- 

 coccus lanceolatus. 



Sometimes it is impossible to detect the point of entrance 

 of pyogenic organisms. In view of the observation that tu- 

 bercle bacilli pass through the uninjured mucosa without leav- 

 ing any local lesion, but setting up the disease in places remote 

 from the point of entrance, it may be surmised that the pyo- 

 genic organisms may enter the body without leaving any trace 

 of their point of entry. 



The severe general symptoms, famihar to every physician, 

 often accompanying acute suppuration, indicate the formation 

 of toxic bacterial products and their absorption. Experimental 

 evidence of the formation of such toxic products is not so 

 clear, however, for the pyogenic organisms as for some of the 

 other bacteria. It has been shown that cultures of Staphy- 

 lococcus pyogenes aureus, in which the bacteria have been 

 killed, are capable of producing suppuration in the lower 

 animals. 



The pyogenic bacteria play a somewhat different part in 



