ESSAYS ON BACTERIOLOGY. 15 



Bacteriology has passed the stage of curiosity and 

 sensation; it is not a scientific by-play nor a micro- 

 scopic diversion; it is a study of pathology and the 

 causation of disease, and as such has taken its place 

 among the branches of medical science and in the 

 curriculum of medical studies. We are all watching 

 it — interested in it, and now that it has become a 

 somewhat old story, must often ask ourselves : What 

 is it doing and what does it propose to do? What 

 problems are before it and how is it endeavoring to 

 solve these problems? 



Laying aside mere details and technicalities, which, 

 after all, attract the intelligent mind the least, I have 

 thought it might be of interest to consider very briefly 

 some of those problems which have been engaging the 

 attention of workers in this line, problems arising in 

 the struggle to overcome obstacles to the further de- 

 velopment of the work, problems involved in the 

 effort to render practically valuable the results already 

 reached. Omitting some which are of much, perhaps 

 of equal, importance, I mention the following: 



Qxiestions of the susceptibility of animals to the in- 

 fectious diseases; the diirability of infectious material; 

 of disinfection ; the manner of dissemination of disease 

 germs; are all infectious diseases due to one specific 

 cause; the qiiestion of hereditary transmission. 



Koch lays down four postulates which must be 

 satisfied before we can fully accept the causative re- 

 lation between a bacterium and a disease. The last 



