378 BACTERIA. 



through the cells. We observed that animals treated by 

 inoculation of the blue pus products and then with anthrax 

 bacillus not only passed through the disease at the time, but 

 they were protected against anthrax, even of a virulent 

 order, when inoculated later. This we looked upon as most 

 interesting, as in other experiments that had been carried on 

 with the blue pus bacillus itself as a protective agent against 

 anthrax, it was found that although an attack of anthrax was 

 cut short in the presence of the blue pus bacillus in a 

 rabbit, it could still be so inoculated at a later date that the 

 animal died with symptoms of true anthrax. The inference 

 we drew was, that the action of the products of the blue 

 pus bacillus and the action of the anthrax albumoses on the 

 cells are essentially different but that the one may interfere 

 with the action of the other. Thus, an animal that has been 

 rendered immune to blue pus is none the less susceptible to 

 anthrax. In our experiments the products of the blue pus , 

 bacillus were injected only at intervals, and during part of 

 the time between these intervals there was little of the 

 substance in the fluids of the body ; during these intervals 

 the albumoses of the anthrax had the opportunity of acting 

 on the tissue cells and of so acclimatizing them to its 

 presence that immunity was conferred. Where, however, 

 the blue pus bacillus was in the body, forming its products 

 continuously and acting antagonistically to the anthrax 

 bacillus, the tissues had never any opportunity of becoming 

 acclimatized to the action of the albumoses and no immunity 

 was conferred. Immunity produced by the attack of a 

 specific disease must then be looked upon as an acquired 

 tolerance or adaptation of the cells of our body to the specific 

 poison of the special bacterium of that disease, and the pro- 

 cess of recoveryfrom an attack of anthrax, for example, is really 

 the development of such immunity, which gradually passes 

 into the more perfect form during the course of the disease 

 and remains after the patient has recovered. The antago- 

 nism of the products of one organism on another which occurs 

 in mixed infection can never in all probability act directly 

 in the body, but through the agency of the cells in the 

 body such action may come to play a most important part 

 in holding in check the active poisons until an immunity can 

 be acquired. On the other hand we may look forward to a 

 period when it will be possible to obtain, by the action of 



