32 BACTERIA IN DAILY LIFE 



indebted to the beautifully simple and ingenious 

 methods devised by Robert Koch. 



Not yet twenty years have passed since the new 

 bacterial examination of water was introduced and 

 systematically employed, and the use which has 

 been made of the opportunities thus opened up of 

 investigating water problems on an entirely new 

 basis is shown by the voluminous dimensions which 

 the literature on this one branch of bacteriology 

 alone has reached. Considerably upwards of two 

 hundred different water bacteria have been isolated, 

 studied, and their distinctive characters chronicled. 

 The behaviour of typhoid, cholera, and other 

 disease-producing microbes in waters of various 

 kinds has been made the subject of exhaustive ex- 

 periments ; the purification power of time-honoured 

 processes in operation at waterworks and elsewhere 

 has been for the first time accurately estimated. 

 Water engineers have through these bacterio- 

 logical researches been provided with a code of 

 conduct drawn up by the light of erudite scientific 

 inquiries, which has now rendered possible the 

 removal of the process of water purification from 

 the rule of empiricism guided by tradition, and to 

 raise it to the level of an intelligent and scientific 

 undertaking. 



The above short sketch may serve to convey 

 some idea of the rise and phenomenal develop- 



