66 THE GERM THEORY OF DISEASE. 



more the matter was discussed, the more certain it seemed 

 that this had been demonstrated. One point of vast import 

 had been attained ; and now the experimentation must pro- 

 ceed from the new basis. Inoculation must be with pure 

 virus of some particular disease ; not a supposed virus mixed 

 with various germs. Otherwise nothing distinctive could be 

 expected. 



As we have said, Pasteur had gained a most happy result 

 from his flask cultures, in the isolation of the bacillus anthrax. 

 But it had cost an immense amount of labor, and shown that 

 the results were very uncertain at best. Besides, there was a 

 serious objection urged against flask cultures, in that small 

 portions of the fermenting fluid were always transferred to 

 the flasks with the organisms. The anti-vitalists claimed 

 that the molecular motion, poison or chemical ferments were 

 carried over by the small portion of fermenting fluid trans- 

 ferred, and that where there were fermentable fluids, this 

 power would be propagated. It is evident that this argu- 

 ment carried with it much force, for such men as Prof. Bill- 

 roth, Prof. Thiersch, and others of the great medical men 

 of the world, still considered this argument a valid one, 

 which still placed the causative effect of micro-organisms in 

 doubt. 



Therefore other means of cultivation were earnestly sought. 

 Dr. Koch, of Berlin, was again the successful man. He de- 

 vised and brought into successful operation the Dry Slide 

 Cultivation, by which the particular organism could be watched 

 during its entire development, by the eye of the experimenter, 

 so that it could be seen, at any stage of the process, whether 

 or not the cultivation was contaminated by other organisms 

 than the one desired. 



The plan was this. Suitable material to serve as food, or 

 soil, for the sustenance of the organism was mixed with 



