iv.] ARTIFICIAL COMMA-BACILLI. 73 



droplet from any part of an early or advanced colony, there 

 are always seen multitudes of actively moving comma-bacilli 

 single or g-shaped and in spirals. A trace taken from the 

 central granular spot or precipitate shows multitudes of - 

 shaped, wavy, or spiral forms more or less intimately matted 

 together in larger or smaller masses. The spirals on drying 

 and staining easily break up into single commas and S" 

 shaped forms. 



Owing to the comparative slowness with which the 

 colonies of comma-bacilli in gelatine plate-cultivations make 

 their appearance, it is clear that if other more rapidly 

 growing bacteria, micrococci, and bacilli, which by their 

 growth are capable of liquefying the gelatine, have been 

 introduced in large numbers into the cultivation, the colonies 

 of the comma-bacilli will be difficult to demonstrate. This 

 is especially the case when one wishes to demonstrate by 

 gelatine plate-cultivation the presence of comma-bacilli in a 

 choleraic stool or in the contents of the ileum of an early 

 cholera case in which the comma-bacilli are originally only 

 sparingly present and are accompanied by multitudes of 

 other bacteria ; and we have already mentioned that this is 

 not at all a rare thing, but on the contrary is more common 

 than the reverse. In such cases the demonstration of the 

 colonies of comma-bacilli in gelatine plates is not very easy 

 of achievement. It is therefore necessary in such cases to 

 dilute considerably with sterilised neutral fluid salt-solution 

 or broth the particle of matter taken from the stool, 

 and from this dilution to inoculate with a droplet the 

 gelatine tube. It is obvious that owing to the relatively 

 small number of comma-bacilli originally present it is 

 necessary for success to start at the same time a series 

 of plate-cultivations. I have seen cases of cholera where 

 out of a dozen of plate-cultivations made by this method, 



