PEEFACE 



The existing literature in connection with the Bacteri- 

 ology of Water is so extensive, and is scattered through 

 such numerous publications both English and foreign, 

 that we venture to think an urgent necessity has arisen 

 for a work in which this subject is specially discussed. 

 We have, therefore, in the following pages endeavoured 

 to present in a connected form an account of the more 

 important investigations which have been carried out 

 in this department of Bacteriology, in the hope that it 

 may prove of service both to the student and inves- 

 tigator, as well as to those who, like engineers and 

 medical officers of health, are practically concerned 

 with the hygienic aspects of water-supply. 



With this object in view, we have given — firstly, a 

 survey of all the more important general methods of 

 bacteriological study, describing in detail those which 

 are specially applicable to the examination of water ; 

 secondly, we have given an account of the principal 

 results hitherto arrived at by the use of these new 

 bacteriological methods in the study of the different 

 kinds of water, and the changes which they undergo 

 through natural and artificial agencies ; further, par- 

 ticular attention has been bestowed on the behaviour 



