Facts bearing on acquired immunity 231 



typhoid bacillus in the peritoneal cavity can be easily prevented by 

 a previous injection, twenty-four hours before, of broth, physiological 

 salt solution, or normal serum. The suppression of phagolysis is, as 

 in the case of vibrios and spirilla, followed by the suppression of 

 extracellular action on the typhoid bacilli. 



The same analogy is observed in the phenomena which appear be- 

 neath the skin. The bacillus of typhoid fever, when introduced into 

 the subcutaneous tissue of vaccinated guinea-pigs, although not appre- 

 ciably injured by the fluid of the exudation, undergoes some agglu- 

 tination. The injurious action of the fluids of the body is here still 

 less effective than in the peritoneal cavity. But, as in the peritoneal 

 cavity of vaccinated guinea-pigs previously treated with broth, so in the 

 subcutaneous exudation it is the phagocytes which destroy the micro- 

 organisms. In both cases there is a very great afflux of leucocytes, 

 mainly microphages. These cells ingest and digest the bacilli, which 

 ultimately disappear. The micro-organisms ingested by the micro- 

 phages, once inside these phagocytes are transformed into granules 

 very like those observed in the cholera vibrio similarly treated. In this 

 respect the analogy between the two micro-organisms is complete. 



Oppel, working in my laboratory, has repeated Cantacuzene's 

 work on the retarding action of opium upon the phagocytic process. 

 He obtained the same results: under the influence of the narcotic, 

 the leucocytes intervened only at a late stage, with the result that 

 the vaccinated guinea-pigs succumbed to the typhoid infection. The 

 same conclusion must be drawn from the experiments made by 

 A. Wassermann 1 . Guinea-pigs that had been immunised against the 

 bacillus of typhoid fever were completely resistant to a dose that was 

 always fatal to the control animals. When, however, along with this 

 dose of bacilli, a certain quantity (3 c.c.) of a serum which hinders 

 the phagocytic reaction is injected, the guinea-pigs lose their im- 

 munity and die from typhoid infection. The serum employed by 

 Wassermann was obtained from rabbits that had been treated with 

 the blood serum of guinea-pigs. Rabbit's serum, thus prepared, 

 neutralises the action of the guinea-pig's cytase, but, as demonstrated [244] 

 by Besredka 2 , it also exercises several other functions, one especially, 

 that of preventing phagocytosis. In Wassermann's experiments it 

 was the autiphagocytic function, then, that was the important factor 



1 Ztschr.f. Hyg^ Leipzig, 1901, Bd. xxxvn, S. 173. 



2 Ann. de I'lnst. Pasteur, Paris, 1901, t. xv, p. 209. 



