236 Chapter VIII 



The exudation becomes more and more abundant at the seat of 

 inoculation and ends in the formation of an abscess, from the contents 

 of which cultures of the Bacillus pyocyaneus may be obtained for 

 a fortnight. The bacilli, however, finally disappear, this being due 

 to the destructive action of the phagocytes and not to that of the 

 fluid of the exudation. 



This fundamental part played by phagocytosis in acquired im- 

 munity against the Bacillus pyocyaneus has been confirmed by 

 Gheorghievvsky by experiments on guinea-i)igs vaccinated and then 

 submitted to the action of opium. As in the analogous experiments 

 of Cantacuz^ne on the cholera vibrio, the opium narcosis retards dia- 

 pedesis and this, for some time, increases the chances of the bacilli. 

 A tardy diapedesis and phagocytosis, no doubt, is produced which ends 

 in the ingestion of the bacilli, but the animal loses its acquired 

 immunity and finally succumbs in spite of the fact that the dose of 

 Bacillus pyocyaneus was insufficient to kill a control guinea-pig vac- 

 cinated to the same degree, but not submitted to the action of opium. 



The example we have just analysed relates, then, to a micro- 

 organism which is more resistant than are the vibrios, Obermeyer's 

 spirilla or even the typhoid bacillus, to the action of the microcytase 

 w^iich has escaped from the cells during phagolysis. The Bacillus 

 pyocyaneus undergoes, in the fluids of the vaccinated animal, the 

 action of the specific fixative and can thus be rendered motionless 

 and become agglutinated. But this action is insufficient to ensure 

 immunity and should phagocytosis not take place in time to ingest 

 the bacilli, the vaccinated animal succumbs. The reaction of the 

 phagocytes is, therefore, indispensable if the acquired immunity is 

 to be effective. In this respect the analogy is very great between 

 the resistance of the vaccinated animal against the various bacteria 

 (vibrios, spirochaetes, typhoid cocco-bacilli, bacilli of blue pus) that 

 we have so far studied in this chapter. These bacteria have, however, 

 [249] this in common ; — they are all endowed with a considerable power 

 of motion. Pursuing our examination of the principal data on 

 acquired immunity against micro-organisms, we must now choose 

 examples from the group of non-motile bacilli; amongst these we 

 assign the first place to the micro-organism of swine erysipelas. This 

 small bacillus has been the subject of several important researches 

 on acquired immunity, one of which at a certain period caused quite 

 a sensation in the bacteriological world. Emmerich^, in an investi- 

 1 Fortschr. d. Med., Berlin, 1888, Bd. vi, S. 729. 



