332 MICRO-ORGANISMS IN WATER 



when introduced into water, and the necessity of diffe- 

 rentiating between these two forms in carr3dng out such 

 researches. Moreover, it cannot be too rigidly insisted 

 upon that every precaution must be taken to avoid the 

 introduction with the organism of any appreciable 

 quantity of culture-material into the experimental 

 waters. It is apparent how entirely the character of 

 tlie water may be modified by a neglect of this precau- 

 tion, and that a water originally incapable of supporting 

 a pathogenic organism in question may be transformed 

 into a suitable medium in which it will not only live 

 but multiply. Unfortunately, many investigators have 

 ignored this possibility, and hence we sometimes find 

 such conflicting information recorded of the behaviour 

 of one and the same organism in water. 



