v.] VARIOUS SPECIES OF COMMA-BACILLI. 95 



experiment, and have had, after a great many failures, 

 one other successful colony produced in plate-cultivation 

 in neutral nutritive gelatine from which a series of tubes of 10 

 per cent, alkaline nutritive gelatine were started. These I 

 have kept growing for many generations, and their behaviour 

 in Agar-agar mixture, in broth, in gelatine, and in potato was 

 carefully noted and compared with cultures of choleraic 

 comma-bacilli ; all I can say is that they appear to me 

 identical. The only difference that I can find is that the 

 comma-bacilli from the colony in the plate-cultivation 

 appeared slightly larger, that is to say, thicker than the 

 choleraic comma-bacilli, but this difference was not so 

 striking in the cultivations in 10 per cent, alkaline gelatine. 

 I maintain then that in the normal fluid of the mouth 

 there occur at least two kinds of comma-bacilli, one very 

 similar to the choleraic comma-bacillus, the other (isolated 

 by Miller) similar to Finkler's. 



III. Deneke described comma-bacilli which he found in 

 stale cheese, and which he afterwards isolated and cultivated. 

 Morphologically, and also in gelatine cultures, they appear 

 almost identical with those of Asiatic cholera, so much so 

 that he failed to observe any describable difference ; in 

 fact, he states that so far as he was able to observe, the only 

 distinction seems to be their different action when injected 

 into guinea-pigs. He afterwards, however, modified this 

 view, inasmuch as Fliigge showed that there are slight 

 differences from the choleraic comma-bacilli in their mode 

 of growth in nutritive gelatine, in which respect they stand 

 about midway between the choleraic and Finkler's comma- 

 bacilli. At any rate this much seems certain, that the 

 differences existing between them and Koch's comma-bacilli 

 are not very great, not so great, in fact, as those between 



