INTRODUCTION 



The advent of bacteriology into the realm of the 

 biological sciences not only brought with it a new 

 conception of the nature of many complicated phe- 

 nomena, such as fermentation and disease, but also 

 placed in the hands of experimental workers a new 

 tool. The method of sterilization, of asepsis, made 

 it possible for the first time to attack problems 

 hitherto incapable of solution, or even of approach. 

 This development of bacteriological technique, of 

 rigid and undeviating adherence to definite rules 

 and principles, is not likely to be passed over lightly 

 by the historian of nineteenth-century science. The 

 art of practical medicine and theoretical medical 

 research alike owe much of their recent brilliant 

 success to a ready adoption of the new method. 



At the present time an active campaign is being 

 set on foot by public health authorities against 

 several widespread and serious diseases of the human 

 race. In various parts of the world, malaria, tuber- 

 culosis, and typhoid fever are being fought energeti- 

 cally and with much success. In these systematic 

 and organized movements the resources of bacteri- 

 ology are being utilized as never before, and a full 

 understanding of technical procedure and devices 

 is deemed essential by all workers in this subject. 

 The problems of water-supply and sewage disposal, 



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