SPIRILLUM CIIOLEIUK ASIATICS. 431 



to such an extent that it has reached, at the surface, 

 the margin of the glass ; after 8 to 14 days the upper 

 two-thirds of the gelatine is liquefied throughout its 

 whole extent. 



On nutrient agar the comma hacilli form a superficial Growth on 

 greyish-yellow, folded gelatinous layer, without any substrata! 10 

 liquefaction of the suhstratum. These agar cultivations 

 etain their vitality for a considerable length of time. 

 On potatoes kept at the ordinary temperature no growth 

 can be observed, but at from 80 to 85 C. a light 

 brown, and later a more greyish-brown, mucous layer is 

 formed. 



The comma bacilli grow very luxuriantly in neutralised 

 meat infusion, in blood serum, and in milk, the latter 

 medium not undergoing any noticeable alteration. In 

 none of these cultivations is there any development of 

 putrefactive gases, nor any disagreeable odour ; there 

 is at most a peculiar aromatic and sweetish smell. 

 (Buchner alone has observed a development of foul 

 smell in his cultivations of comma bacilli in meat 

 infusion.) 



On the whole the comma bacilli are not very fastidious Behaviour in 

 as regards the composition of the nutrient substrata. tions^ndTn 

 It is not till the nutrient solutions become very dilute water - 

 that the growth ceases. As a rule no multiplication of 

 comma bacilli takes place in infusions of the strength 

 ordinarily employed for cultivations if diluted with 40 

 parts of water, while with somewhat greater concentra- 

 tion active growth occurs; in the former case there is a 

 gradual diminution in the number of the organisms in- 

 troduced. In water,* even when it contains a relatively 

 large amount of organic and inorganic material in solu- 

 tion, there is never any multiplication of the comma 

 bacilli. It is only where, at the margin of stag- 

 nant water, there is a local accumulation of nutrient 

 materials from the presence of a variety of solid particles 

 in suspension and of pieces of mud that development 

 occurs, and this takes place especially on the floating 

 solid pieces, and thus for example wo have the explana- 



* According to experiments by Bolton, Ztitschrf. Jfygitne, vol. iv. 



