CHOLERA. 187 



albuminoid materials on which the organism lives), alum, I per cent., 

 camphor, .33 per cent., carbolic acid, .25 per cent., essence of peppermint, 

 .5 per mille, sulphate of copper, 4 per mille, quinine, .2 per mille, corrosive 

 sublimate, I per cent. 



Babes has found that the organisms will not develop in a gelatine 

 nutrient medium which contains .5 per mille of corrosive sublimate, .1 per 

 mille of carbolic acid, .2 per mille of sulphate of copper, .8 per mille of 

 salycilic acid, .1 per mille of thymol, 2 per mille of iodine, 2.2 per mille of 

 bromine, 7 per cent, of alcohol, .8 per mille of sulphate of quinine, .5 per mille 

 of acetic acid (the action of which, however, depends to a certain extent upon 

 its interference with the degree of alkalinity of the original gelatine, as the 

 bacillus cannot grow in a medium in which there is more than a merely 

 appreciable trace of acidity). He also tried a very interesting experiment 

 in which he inverted a gelatine plate on which was placed a cholera 

 culture over a watch glass or shallow vessel containing a drop of essential 

 oil of mustard ; no development of the organism took place, and if the 

 plate was left for twenty-four hours the organisms were all killed, as there 

 was no subsequent development ; so that oil of mustard is an excellent 

 disinfectant. Other active volatile principles act in very much the same 

 manner. 



The experiments with gelatine cultures are of special value 

 because they allow demonstration of the effect that disinfec- 

 tants have on the bacillus as it grows on specially favour- 

 able nutrient media. Reference has already been made to the 

 fact that putrefactive organisms and their products exert a 

 prejudicial effect on the cholera organism, but it should be 

 remembered that when the conditions are favourable there is 

 usually such rapid proliferation of the cholera organism for 

 the first day or two, that the others are left behind in the 

 race for existence. It is, however, a case of the hare and 

 the tortoise, for after a time the cholera organisms die out, 

 and never again obtain a permanent footing unless a fresh 

 supply of nutrient material becomes accessible. It is im- 

 portant to remember this in connection with the spread 

 of cholera by water supply, as it explains the immunity 

 enjoyed, after a time, even in the most cholera-stricken 

 regions. In India, in the regions in which the cholera is 

 endemic, the wells, as a rule, are merely surface tanks into 

 which sewage and surface water may be drained, and 

 which are frequently on the same level as, and connected 

 with, the cesspools, so that even the water supply contains a 

 considerable quantity of organic matter in which organisms 

 of all kinds can flourish most luxuriantly ; whilst these same 

 wells, being merely dug-out pits beneath the slightly raised 

 houses, are open for the reception of sewage and excreta 



