Immunity against micro-organisms 307 



certain direct action of the substances contained in this fluid, there 

 still remain a whole series of processes, amongst which the carriers of 

 the cytases, that is to say the phagocytes, fill the most important role. 

 Nevertheless, the cholera vibrio with its allied forms is still the most 

 sensitive of all the micro-organisms to the bactericidal action of the 

 fluids of the body. It may, therefore, readily be conceived that the 

 more resistant micro-organisms are even less subject to the direct 

 influence of the specific serums. Thus we have seen that the cocco- 

 bacillus of typhoid fever presents, in the phagolysed peritoneal fluid, 

 merely an attenuated form of Pfeiffer's phenomenon. The other 

 representatives of the group of bacilli are still less subject to the 

 direct action of the serums, and Gheorghiewsky 1 , in his studies on 

 the Bacillus pyocyaneus, found that normal guinea-pigs, injected 

 subcutaneously with anti-infective specific serum, and inoculated into 

 the peritoneal cavity with this organism, present the same phenomena 

 as those described in Chapter VIII. He never noticed either lysis 

 of the bacteria in the fluids of the animal or their total transforma- 

 tion into agglutinated masses outside the phagocytes. The resistance 

 offered by the animal was always in direct relation to the rapidity of 

 the appearance and extent of the phagocytic reaction. 



In order to determine the relative importance of each of the factors 

 which act in the preservation of animals subjected to the influence 

 of the specific serum, Gheorghiewsky repeated Cantacuzene's experi- [323] 

 ments on the effect of narcotisation by tincture of opium. This alkaloid 

 retards diapedesis, but does not affect the tactile sensibility or the 

 motility of the leucocytes. The humoral properties, on the other 

 hand, are not in the least affected by the narcosis. In spite of the 

 fact that in guinea-pigs, narcotised and treated with anti-infective 

 serum, the direct action was not interfered with, the animals always 

 died because the retarded and incomplete phagocytic reaction was 

 insufficient to destroy the bacilli rapidly enough. 



Mesnil 2 studied the action of the specific serum against swine 

 erysipelas on normal animals into which he had injected it some time 

 before inoculation of the corresponding bacillus into the peritoneal 

 cavity. This serum exercises a most marked protective action on the 

 mouse, an animal very susceptible to the pathogenic action of this 

 micro-organism. In mice so prepared complete and rapid phago- 

 cytosis takes place. These micro-organisms before being ingested 



1 Ann. de Vlnst. Pasteur, Paris, 1899, t. xm, p. 312. 



2 Ann. de llnst. Pasteur, Paris, 1898, t. xn, p. 492. 



202 



