BACTERIA IN INFECTIOUS DISEASES. 255 



cayed teeth and of organic material, from neglect 

 of the tooth-brush, may favor the development of 

 putrefactive bacteria, which are fatal to the spe- 

 cies of micrococcus which produces septicaemia in 

 rabbits. Differences in habit as to the expectora- 

 tion of the saliva or retaining it in the oral cavity, 

 and as to breathing through the nose or through 

 the mouth, will also constitute differences in the 

 environment of the micrococcus which can scarcely 

 fail to have an influence upon its physiological 

 characters. When the flow of saliva is rapid, and 

 it is not long retained in the mouth, it is evident 

 that an organism which multiplies rapidly will 

 have the advantage of one which multiplies slowly 

 and may survive where the other would quickly 

 disappear. There will also be a constant ten- 

 dency to develop still further this capacity for 

 rapid multiplication, which no doubt is an impor- 

 tant, if not the essential, factor in giving to a 

 micro-organism pathogenic power. The impor- 

 tance of this factor will be appreciated when we 

 remember that one method by which nature limits 

 the power for mischief of putrefactive bacteria 

 injected into the tissues is by a conservative 

 inflammatory process, which builds a wall about 

 the invading parasites, and confines their depreda- 

 tions within the narrow limits of an abscess. In 

 the disease produced by inoculation with saliva, or 

 with a culture-fluid containing the micrococcus 

 under consideration, owing perhaps to the rapid 

 development of the micrococcus, no such limiting 



