THE BIOLOGY OF BACTERIA 33 



various changes in the body of an inflammatory nature. It 

 is not yet possible to say in what way or to what degree the 

 association of bacteria influences their role. That is a pro- 

 blem for the future. But whilst we have examples of this as- 

 sociation in streptococcus and the bacillus of diphtheria, B. 

 coli and yeasts, tetanus and putrefactive bacteria, Diplococ- 

 cus pneumonia and streptococcus, and association amongst 

 the various suppurative organisms, we cannot doubt that 

 there is an explanation to be found here of many hitherto 

 unsolved results of bacterial action. This is the place in 

 which mention should also be made of higher organisms as- 

 sociated for a specific purpose with bacteria. There is some 

 evidence to support the belief that some of the Leptotricheae 

 (Crenothrix,Beggiatoa, Leptothrix,etc.)and the Cladotricheae 

 (Cladothrix) perform a preliminary disintegration of organic 

 matter before the decomposing bacteria commence their 

 labours. This occurs apparently in the self-purification of 

 rivers, as well as in polluted soils. 



Antagonism of Bacteria. Study of the life-history of 

 many of the water bacteria will reveal the fact that they 

 can live and multiply under conditions which would at once 

 prove fatal to other species. Some of these water organisms 

 can indeed increase and multiply in distilled water, whereas 

 it is known that other species cannot even live in distilled 

 water, owing to the lack of pabulum. Thus we see that 

 what is favourable for one species may be the reverse for 

 another. 



Further, we shall have opportunity of observing, when 

 considering the bacteriology of water and sewage, that there 

 is in these media in nature a keen struggle for the survival 

 of the fittest bacteria for each special medium. In a carcass 

 it is the same. If saprophytic bacteria are present with 

 pathogenic, there is a struggle for the survival of the latter. 

 Now whilst this is in part due to a competition owing to a 

 limited food supply and an unlimited population, as occurs 



