16 THE BACTERIA IN ASIATIC CHOLERA. [CH. 



the absence of growth, and thought that the broth must be 

 the cause of it, for I have never met with anything like this 

 before in the case of other bacteria. For instance, anthrax- 

 bacilli can be kept in store for a long time dry on cover- 

 glasses ; they retain vitality from half a week to nearly a 

 whole week in this manner. As, however, the meat- broth 

 on examination proved to be unexceptionable, we had to 

 examine whether the comma-bacilli had not probably died 

 off owing to being dried upon the cover-glass. In order to 

 obtain certainty on this point, the following experiment was 

 made. A number of cover-glasses were provided with a 

 small drop of substance containing bacilli. The drop dried 

 up in a few minutes. One cover-glass was now charged 

 with a drop of meat-broth after an interval of a quarter of 

 an hour, another after an interval of half an hour, another 

 after an interval of an hour, and so on. Then it was seen (and 

 I made several series of experiments) that the comma-bacilli 

 did come to development on the dried glass plates that had 

 lain a quarter, a half, and a whole hour, but after two hours 

 they sometimes died off; after three hours, I could not keep 

 the bacilli alive in these experiments. Only when compact 

 masses of bacilli-cultivations for instance, when the pulpy 

 substance of a cultivation made on potatoes was dried did 

 the bacilli retain vitality for a longer time ; clearly because 

 in this case complete desiccation followed much later. But 

 even under these conditions I have never succeeded in 

 preserving the bacilli alive in a dried state longer than 

 twenty-four hours. 



" This result was so far important, that by its means it 

 could easily be tested whether the bacteria have a resting 

 state. We know that other pathogenic bacteria for 

 example, anthrax-bacteria, which form spores can be 

 preserved for years in a dry state on a cover-glass without 



