XL] BACILLUS : PATHOGENIC FORMS. 175 



of the ileum by the method of plate-cultivation in nutritive 

 gelatine described in Chapter V. The appearances presented 

 by these comma-bacilli in such plate-cultivations are charac- 

 teristic ; they are shown in Fig. 95, but it is also shown 

 there that a similar character is exhibited by some micro- 

 cocci. These comma-bacilli multiply readily in the mucus- 

 flakes taken from the lower part of the ileum of a person dead 

 of acute cholera if these flakes are placed and kept on moist 

 linen in a moist chamber. 



The comma-bacilli grow and multiply well in neutral 

 broth, neutral nutritive gelatine, neutral Agar-Agar mixture. 



FIG. 96. FROM A PREPARATION OF Mucus FLAKES OF THE FLUID IN THE 

 ILEUM OF A CASE OF TYPICAL CHOLERA. 



Numbers of comma-bacilli of different lengths are shown amongst numbers of small 

 straight bacilli. Magnifying power about 700. 



An alkaline condition is not essential, as maintained by Koch, 

 although, like other bacteria, notably putrefactive bacteria, 

 they grow more luxuriantly if the medium is faintly alkaline. 

 They grow well in milk, on potato (although the reaction 

 of this latter is acid), and I have seen them grow even in 

 faintly acid peptone broth. 



The comma-bacillus of Koch is a curved rod of almost 

 uniform thickness, sometimes slightly pointed at the 

 extremities, its length about half that of a tubercle-bacillus, 

 its thickness about the same as that of the latter. But 

 the comma-bacilli vary in curvature and length within 



