Physiology of Pathogenic Microbes. 69 



concomitant disease exerts upon the course of an- 

 other infectious disease. 



In the case of tetanus, however, the association of 

 accessory germs, such as the bacillus prodigiosus, 

 renders more certain the irruption of the disease, by 

 provoking diapedesis, because the medium then be- 

 comes more favorable to the multiplication and nu- 

 trition of the tetanus bacillus. 



On the other hand, the presence of phlogogenic 

 germs, which excite an excessive diapedesis, may op- 

 pose the receptivity for a given microbe. Thus, re- 

 covery from malignant pustule nearly always occurs 

 after the appearance of suppuration ; this is explained 

 by the fact that the white corpuscles, whose accumu- 

 lation is brought about by the foreign germs, over- 

 come the bacteridium. 



Receptivity of the tissues and organs. — Pathogenic 

 germs do not act in the same manner upon all parts 

 of a susceptible organism; they appear to have a sort 

 of affinity for certain organs, for certain tissues. 

 Thus, the bacillus of bacteridian charbon multiplies 

 in the blood whilst that of symptomatic charbon only 

 develops in the connective and muscular tissue and 

 is, on the contrary, killed in the blood. 



The pneumococcus generally limits its field of 

 operations to the lung; the bacillus of pneumo- 

 enteritis to the lung and the intestine; that of glan- 

 ders to the respiratory apparatus and to the skin, etc. 

 This elective action of pathogenic microbes has, in 

 some cases only, received a scientific explanation. 



When the germs have penetrated into the blood 

 they will localize themselves preferably in the organs 



