HISTORY * 19 



The first opinion upon the relation of specific disease- 

 producing bacteria came in the middle of the eighteenth 

 century, but such a theory could not be proven until 

 about thirty years ago, when Koch made it possible 

 to separate the various individual bacterial species 

 and enabled us, by a series of postulates, to study the 

 relation of the germs to their particular disease. The 

 great proof of the existence of bacteria came from 

 the man who may be considered the founder of the 

 modern science of bacteriology, Louis Pasteur, a 

 French chemist, who demonstrated beyond question 

 that bacteria produce fermentation, and that fer- 

 mentable materials, if protected from the air, remain 

 without bacteria. There succeeded to this proof 

 others to the effect that bacteria are ubiquitous, 

 and that they are carried in dust or probably 

 alone by air currents. His experiments also showed 

 that spontaneous generation (the arising of living 

 forms anew from the elements of nature, and not 

 from preexisting living forms) does not occur. The 

 results of Pasteur's work received practical applica- 

 tion also at the hands of Koch and Lister. The former 

 devised methods for the cultivation and study of the 

 individual species and followed this up by discovering 

 the organisms causing tuberculosis, anthrax, and 

 cholera. Lister, shocked by the appalling mortality 

 in the hospitals from gangrene and septic poisoning, 

 established methods by which bacteria from the air 

 and from infected cases were excluded from healthy 

 surgical cases. To him the basic principles of modern 

 antiseptic and aseptic surgery are due. 



Throughout all the history of microbiological devel- 



