432 



SPIRILLUM CHOLERA ASIATICS. 



Relation to 

 oxygen. 



tion of the observation made by Koch, which will be 

 referred to again, as to the multiplication of comma 

 bacilli in a tank in India. The comma bacilli are also 

 sensitive as regards any acid reaction of the nutrient 

 medium ; the meat infusion, nutrient jelly, &c., 

 employed for cultivations must be accurately neutralised, 

 or, better, slightly alkaline. 



The comma bacilli belong to the aerobes in so far as 

 they only develop with great activity at the surface of 

 fluid or solid nutrient substrata, where they are in con- 

 tact with the oxygen of the air ; it also appears as if they 

 only moved actively in the presence of a certain amount 

 of oxygen. Nevertheless their necessity for oxygen is 

 by no means so great that they cease entirely to multiply 

 where that gas is limited in amount or entirely absent ; 

 on the contrary, in that case the colonies only grow 

 somewhat more slowly and to a less extent than those 

 which have developed in the presence of air. Thus in 

 gelatine plates which are covered with thin plates of 

 mica, and in gelatine tubes from which the oxygen has 

 been expelled by means of hydrogen, a delayed growth 

 of the comma bacilli occurs, though ultimately one 

 quite visible to the naked eye;* and it is this slight 

 sensitiveness with regard to oxygen that enables the 

 comma bacilli to multiply to a great degree under all 

 circumstances, and even in the varying and often rela- 

 tively slight amount of oxygen which they find in the 

 intestinal canal. 



The temperature has an important influence on the 

 temperature. g rowt ^ O f t ^ e cultivations. According to Koch's experi- 

 ments no growth occurs below 16 C.; at 16 or 17 C. 

 growth is slight, and it does not begin to be active till 

 about 17 or 18 C.; much better culture results are 

 obtained, however, with temperatures between 22 and 

 25 C., and this is the temperature at which the gelatine 

 cultivations should be kept if possible; the optimum of 

 temperature is considerably higher, namely, between 30 

 and 40 C., a temperature at which the gelatine becomes 

 completely fluid. 



* Liborius, Zeitschr.f. Hygiene, vol. i. 



Influence of 



