HISTORY 19 



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 the 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) of bacteria does not 

 occur. The results of Pasteur's work received prac- 

 tical application 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 prin- 

 ciples of modern antiseptic and aseptic surgery are due. 

 Throughout all the history of microbiological devel- 

 opment it has been possible to progress more rapidly 

 and definitely with bacteria than with protozoa. 

 Bacterial life and activity can be controlled very 



