ii6 THE BACTERIA IN ASIATIC CHOLERA. [CH. 



of bacteria, and amongst these some species of bacilli and 

 micrococci characterized by rapid growth, and by the capability 

 of rapidly liquefying the gelatine, even if in such a mixture 

 a small number of choleraic comma-bacilli be present, there 

 will be great difficulty in rearing them as colonies in a 

 plate-cultivation. To establish a successful plate-cultivation 

 the number of bacteria introduced into one plate must of 

 course be limited, and the chances are small indeed that 

 more than one or two comma-bacilli are present in a trace 

 of a droplet of a mixture that teems with different species of 

 other bacteria. In such a plate-cultivation, owing to the very 

 slow growth of the choleraic comma-bacilli as compared with 

 many other putrefactive bacteria, and owing to the fact that 

 some of these latter rapidly permeate and liquefy the gelatine, 

 the appearance of the characteristic colonies of the choleraic 

 comma-bacilli will be interfered with. A case like this, then 

 and it is by no means rare does not offer very great prospect 

 of success even at the hands of experts in the method, and 

 the microscopic demonstration of comma-bacilli alone can 

 of course be of no diagnostic value, as every one with Koch 

 will readily admit. I have made a series of observations 

 which prove to me that although choleraic comma-bacilli are 

 present in a bacterial mixture, their demonstration by the 

 gelatine culture-test is extremely difficult, or well-nigh im- 

 possible. From normal human faecal matter a mixture was 

 made in 200 to 300 ccm. of distilled water, the mixture 

 being of thickish semi-fluid character. This mixture in every 

 trace of a droplet teemed with bacteria ; to it were added ten 

 drops of a pure culture in nutritive gelatine of choleraic 

 comma-bacilli. A series of twelve plate-cultivations was 

 then established after the usual methods of dilution, but in 

 none could any colonies of choleraic comma-bacilli be 

 detected. After a few days in all the plates the gelatine 

 was liquefied and was seething with bacilli and micrococci. 



