IMMUNITY 



rarely found in the normal body-fluids, this destructive action 

 ought not to take place in these nor in any position except the 

 peritoneum. As a matter of fact, if the immune guinea-pig is 

 injected under the skin, in the anterior chamber of the eye, or 

 in the fluid of a passive oedema, the phenomenon does not 

 take place : the immune-body is present, but not the comple- 



FIG. 68. Cholera vibrios phagocyted 

 by a macrophage of the guinea-pig 

 and not yet transformed into 

 granules. ( Metchnikoff.) 



FIG. 69. Cholera vibrios 

 phagocyted by a 

 microphage of the 

 guinea-pig and 

 turned into granules. 

 (Metchnikoff. ) 



ment. When this latter is added in the form of a little fresh 

 serum, the transformation into granules occurs. 



Why then does the phenomenon occur in the peritoneum if 

 the complement remains inside the leucocytes ? It is because 

 the mere act of intraperitoneal injection produces phagolysis. 

 The injection of any liquid into the peritoneum, water or 

 nutrient broth, for example, destroys some at least of the 

 leucocytes which are found in it : they discharge, as is known, 

 one ferment under these conditions, that which produces 

 coagulation of the blood ; in the same way, they discharge this 

 other ferment, the complement, which acts upon the sensitized 

 vibrio. 



If then this initial phagolysis could be prevented, the 

 phenomenon of Pfeiffer would also fail. Experiment has 

 proved this : by injecting into the peritoneum sterile broth, 

 freshly prepared and tepid, the leucocytes are rendered much 

 less sensitive to a succeeding injection, and in the peritoneum 

 thus habituated, thus " prepared," Pfeiffer's phenomenon does 



