154 THE BACTERIA IN ASIATIC CHOLERA. [CH. 



It will be remembered that Koch, while in Calcutta, 

 reported to his Government, the substance of which appeared 

 in the Englishman of Calcutta, on the i8th February 1884, 

 that cholera having broken out in one of the bustees 

 surrounding a tank in a suburb of Calcutta, he visited 

 this bustee and found numerous comma-bacilli in its 

 tank. On a second visit, a week later, the epidemic being 

 on the decline, he found much fewer comma-bacilli in the 

 water, and this seemed to him and the Englishman to 

 furnish a positive and remarkable proof that these comma- 

 bacilli stood in an intimate relation to the cause of the 

 cholera outbreak. It is known to all who have been in 

 India, and it has been mentioned on a former page, that 

 the natives use the water of every tank, ditch, and pool, 

 however dirty it may appear to a European, for all kinds of 

 purposes, bathing, washing of mouth, washing of domestic 

 utensils, washing of clothes and linen, not even drinking 

 excepted. This particular tank visited by Koch, is, like 

 most other tanks, surrounded by huts, and is used as a sort 

 of common reservoir into which the evacuations of man and 

 beast, and every kind of domestic filth, find access. That 

 the water of such a tank, around which cholera cases occur, 

 and into which the evacuations of cholera patients find 

 access, and in which the clothes soiled with cholera-dejecta 

 are washed, should contain the same comma-bacilli that 

 are present in the choleraic evacuations is what one 

 would naturally expect, and likewise that the number of 

 these comma-bacilli should be fewer the fewer the cholera 

 cases, i.e. the smaller the number of comma-bacilli thrown 

 into the water. But to conclude, as Koch does, that because 

 there are comma-bacilli in the water cholera cases occur 

 amongst the people using the water, and as soon as the 

 number of the comma-bacilli decreases in the water the 



