278 BACTERIA IN INFECTIOUS DISEASES. 



sanguine as to the possibility of extending the ap- 

 plication of the method to other infectious diseases, 

 and points out that even in anthrax no general 

 law of immunity has been established; as several 

 observers (Lceffler, Gotti, Guilebeau, and Klein) 

 have shown that no such immunity is obtained in 

 the case of guinea-pigs, rats, mice, and rabbits, 

 and that thus far only sheep and cattle have been 

 proved to acquire immunity from inoculations 

 with attenuated virus. 



An interesting question, which has not yet been 

 definitely decided by experiment, relates to the 

 possible protection of an animal which has suffered 

 an attack of one form of septicaemia e.g., an- 

 thrax from the other allied forms. Certainly 

 the infectious septicaemia of rabbits, due to a mi- 

 crococcus, which the writer has especially studied, 

 bears a strong resemblance, in many particulars, 

 to anthrax, and the same may be said of the form 

 of septicaemia in mice, due to a minute bacillus, 

 which has been described by Koch. The question 

 is whether an animal which has recovered from a 

 modified form of one of these diseases will not be 

 protected from the others. If so, it is extremely 

 probable that protection results from tolerance to 

 the chemical poison evolved during the growth ot 

 the micro-organism, and consequent ability on the 

 part of the tissues to withstand the attacks of the 

 parasite, rather than to the using up of some ma- 

 terial in the body of the animal which is essential 

 for the development of the microbe. In this case 



