The Character of the Flagella 343 



(2) Their assistance in differentiating closely allied species. 

 Lukscli'' in differentiating Bacillus typhi abdominalis and 

 Bacillus coli communis made use of their flagella. He 

 found from one to three flagella on the colon bacteria, but the 

 typhoid bacilli were endowed with from 8 to 12 filaments, a 

 difference sufficiently great to be of differential value. He 

 experienced much more difficulty in staining the flagella on 

 the colon germ than on any of the other motile bacteria. 



TaveP* has recently made the statement that Bacillus 

 coli communis has no flagella* but that the typhoid bacillus is 

 provided with them. This statement is qualified by a preced- 

 ing one, that Bacillus coli communis is a non-motile organ- 

 ism, which would indicate that he was working with a differ- 

 ent species. 



In the articles, already mentioned, on the demonstration of 

 the flagella a brief description is given of the motile append- 

 ages on the typhoid and a few other bacteria. Dallinger* and 

 Zettnow'* have discussed the flagella on a few species, more 

 especially the saprophytic spirilla. In addition to these, there 

 are brief mentions of the filaments on the typhoid and other 

 species of bacteria scattered throughout the literature of the 

 past three years, but so far as I am aware, they are too incom- 

 plete to be considered of an}' specific value. 



THE COMPARATIVE DIFFERENTIAL VALUE OF THE FLAGELLA AND 

 THE BIOLOGICAL PROPERTIES OF THE BACILLUS CHOLERA SUIS, 

 B. COLI COMMUNIS, AND B. TYPHI ABDOMINALIS. 



Bacteriology recognizes more fully, perhaps, than any other 

 branch of biological science, functional properties in the forma- 

 tion of species and varieties. There are writers on this sub- 

 ject who consider every variation in the characters or proper- 

 ties of bacteria of specific or varietal significance, while there 

 are others who hold more rigidly to the morphology of these 

 organisms in determining their specific differences. The 

 question, therefore, are specific differences in bacteria deter- 

 mined by their morphological characters or by their biological 



* In 1891 I published a brief description of the flagella on the colon 

 bacteria (Proceedings of the Am. See. of Microscopists, 1891). 



