MECHANISM IN INFECTIONS WITH TRUE PARASITES 85 



If the infection of the guinea-pig is started subcutaneously instead 

 of intraperitoneally the picture is somewhat different. In this case 

 a primary destruction of the organisms, comparable to what occurs 

 in the peritoneal cavity, is not seen; on the contrary, there is active 

 multiplication from the start. The explanation of this difference is 

 no doubt to be sought in the greater difficulties which would present 

 themselves to a prompt collection of cells and serum at the point of 

 attack. 



In either event the infection, when once it has started, progresses 

 without resistance and ultimately leads to the death of the animal. 

 How this is brought about is unknown. So much, however, seems 

 to be certain that unlike the infections with the so-called necropara- 

 sites (tetanus, diphtheria, botulismus) toxins do not play a role in 

 anthrax, and we can accordingly only say that the fatal end in infec- 

 tions of this order must result in an indirect w r ay. Significant in 

 this connection is the fact that anthrax infection in animals that 

 are naturally somewhat resistant, or in others in which a certain 

 degree of resistance has been artificially produced, is followed by 

 symptoms of actual disease and a gradual decline in health until 

 death ultimately occurs. 



Similar considerations apply to infections with streptococci and 

 possibly also pneumococci. While culture streptococci readily 

 succumb to phagocytosis, the animalized organism is highly resistant. 

 But while the anthrax bacillus (in the absence of aggressins) is readily 

 destroyed by living leukocytes aphagocitically (i. e., without phago- 

 cytosis, through the agency of the liberated leukins), this does not 

 occur in the case of the streptococcus. Against this organism the 

 body apparently possesses no defence excepting the phagocytic 

 function of the leukocytes, and this the truly infectious strepto- 

 coccus can overcome only too readily through the agency of its 

 aggressins\ The importance of the latter will be appreciated, if 

 we bear in mind that a streptococcus exudate, which has been ren- 

 dered cell- and bacterium-free by centrifugation, is capable, in suit- 

 able quantity, of completely inhibiting the bacteriotppins of a 

 corresponding immune serum and of thus preventing phagocytosis 

 and bacterial destruction through this agency. / 



In this respect there is a striking difference between the truly 

 infectious and the non-infectious or merely locally infectious strepto- 

 coccus, for on adding aggressin from an infectious to a non-infectious 

 strain the latter is not protected against phagocytosis. 



