CHAP TEE Y. 



ELIMINATION OF PATHOGENIC MICROORGANSIMS. 



THE probable existence of pathogenic microbes in the healthy 

 body, and the spontaneous subsidence of many infective processes, 

 make it important to consider the ways and means by which patho- 

 genic microorganisms are rendered harmless in the living body, or 

 are removed by elimination through some of the secretory organs. 

 It is not at all improbable that the localization which bacteria effect 

 may come to play an important part in the study of micro-parasitic 

 pathology. Whatever be the explanation, there is no doubt that 

 the microorganisms hitherto found have various relations with the 

 tissues. 



In all infective processes in which life is not destroyed, and the 

 products of inflammation do not find their way to the surface 

 spontaneously or by treatment, the microbes are removed with the 

 excretions as dead foreign bodies, or are eliminated through some 

 of the excretory organs in an active state. 



1. Phagocytosis. 



Metschnikoff introduced the term " phagocytosis' 7 to designate 

 the destruction of microbes within the organism by leucocytes and 

 the fixed tissue-cells. 



Wyssokowitsch (" Ueber die Schicksale der ins Blut injicirten 

 Microorganismen im Korper der Warmbluter," 7 J eitsohrift f. 

 Hygiene, Band i. S. 1-45) has studied experimentally the destiny 

 of microorganisms injected into the blood of warm-blooded animals, 

 and found that they were not eliminated. He demonstrated by 

 microscopical examination of the blood and by cultivation experi- 

 ments, that the microbes disappear entirely from the blood or 

 diminish greatly in number soon after intravenous injection. The 

 saprophytes disappear soonest. The toxic bacteria are slowest in 

 disappearing and seldom leave the blood entirely. After a brief 

 period, when their number is at a minimum, they again reappear 

 in the blood and multiply with great rapidity until they kill the 

 animal. Examination of the urine during life and soon after 

 death showed that elimination of bacteria through the kidneys did 

 not take place ; that, on the other hand, the urine contained bac-. 



