ESSAYS ON BACTERIOLOGY. 47 



panied by tlie formation of new chemical bodies, but 

 that through the agency of these substances the fer- 

 mentation is stopped. In a word, the process is self- 

 limiting ; the ferment is drowned, or benumbed, in its 

 'Own products. Some of these bodies are known; they 

 are recognizable by ordinary chemical methods, and 

 by their use we may imitate, artificially and exactly, 

 the natural self-limitation of the processes by which 

 they are produced. All this is true of the ordinary 

 alcoholic fermentation. 



Of course, the question arose whether something of 

 the same kind might not explain the phenomena of 

 the self-limited diseases. Might it not be that the 

 new compounds resulting from the growth of the 

 germs in the body, either by altering the soil on which 

 they grow or actually poisoning them, bring the dis- 

 ease to an end, and thus be explained one of the great- 

 est direct life-saving agencies known to man? Cer- 

 tainly the analogy from the fermentation would seem 

 to warrant the inference which experiments, so far 

 made, tend only to confirm. It might be said that 

 the apparent self-limitation is no real self-limitation, 

 but only a subsidence of the disease accompanying the 

 completion of the cycle of the germ's natural life- 

 history. But such an explanation is untenable, for 

 there is no such cycle of life-history in the sense just 

 indicated. Given the proper conditions and suitable 

 food, and the germs will continue to multiply and re- 

 produce themselves indefinitely. ISTor is the theory 



