ESSAYS ON BACTERIOLOGY. 71 



the prospect is inviting ; progress brings a constant suc- 

 cession of fulfilled expectations, equally unexpected 

 disappointments, startling surprises, suddenly opening 

 avenues for the advance, and that the final results will 

 be great and good no one can doubt. 



We are still confronted by the difficulty in making 

 satisfactory inoculation tests in several of the impor- 

 tant diseases, the specific bacteria of which are all but 

 demonstrated. This is still true of typhoid fever and 

 Asiatic cholera. So far as we know, animals are not 

 siibject to these diseases, at least not in a definitely 

 recognizable form. While, therefore, there can be 

 little doubt that tlie Koch-Eberth bacillus and the 

 Koch spirillum are the genuine exciters of these dis- 

 eases, the final and absolute step in the demonstration 

 remains to be taken. Several bold experimenters 

 have swallowed fresh cultures of cholera spirilla, in 

 several instances inducing moderate attacks of a dis- 

 order similar to cholera, with swarms of the organ- 

 isms in the stools. Among these daring men was the 

 veteran Pettenkofer, whose object was to show that 

 other factors than the germs were at least active in 

 the production of the disease. In one instance, under 

 the observation of the well-known Metschnikoff , a man 

 in Paris induced a typical attack of cholera by swal- 

 lowing a pure culture, and that in the absence of chol- 

 era in Paris at the time. This is held by some to be 

 conclusive evidence; but we can hardly be satisfied 

 without a more thorough test. 



