THEORIES OF IMMUNITY. 



performed their functions there, while the en- 

 globing and digestive action of the phagocytes 

 was a secondary process. 



PfeifFer's phenomenon seemed to show, how- 

 ever, that there was no cell action whatever 

 necessary in the production of immunity, for it 

 took place in a fluid apparently entirely free from 

 cells. It consisted (Zeit. f. Hyg., 1894, T. XYIL, 

 pp. 1, 355) in the following: In working to 

 secure immunity in guinea-pigs against experi- 

 mental cholera he found that living and virulent 

 cholera spirilla injected into the peritoneal cav- 

 ity of a fresh gninea-pig together with a small 

 amount of the serum of an immunized guinea- 

 pig, and then examined at short intervals, became 

 bunched together, granular, and finally disap- 

 peared entirely. This destruction he claimed to 

 depend entirely upon the action of the body fluids, 

 and to be the result of the action of a substance 

 wholly different from the alexines of Buchner; 

 the immune serum in an inactive state did not 

 contain it by itself, but as soon as it was intro- 

 duced into the tissues of a fresh animal, the bac- 

 tericidal substance undergoes some change as a 



29 



