CHOLERA. 163 



dogs, poultry and other animals with cholera dejecta and 

 with comma bacilli ; in' no case could he produce cholera, 

 and on search being made for the bacilli in the stomach and 

 intestine, they were invariably absent, apparently having 

 been destroyed in the stomach, as in only a few instances did 

 they reach the intestine at all, and then in very small 

 numbers. To demonstrate the difference between these and 

 certain other bacteria, a mouse was fed with a red micro- 

 organism that had been isolated in a pure condition ; and 

 after a time its intestinal contents were disseminated on 

 potatoes, on which small red colonies of the same organism 

 shortly made their appearance, showing that their vitality 

 was not appreciably affected by their passage through the 

 stomach. Having found that the comma bacillus was so 

 destroyed, Koch thought that if the organism could be intro- 

 duced directly into the large intestine, so as to escape the action 

 of the gastric juice, it might be able to retain its vitality 

 and multiply ; the results obtained, however, were in all 

 cases negative, even when purgatives were previously given 

 to induce an altered condition of the intestine. The only 

 cases in which partially successful results were obtained were 

 those of a series of rabbits into which pure cultivations of 

 the bacillus were injected directly into the circulation, and 

 of a number of mice, in which the cultivations were injected 

 into the abdominal cavity ; the rabbits recovered in one or 

 two days, after suffering from marked symptoms of intoxi- 

 cation ; but the mice died at the end of the first or second 

 day, bacilli in these experiments being found in the blood. 

 Koch argued from these observations (i) that the gastric 

 juice of the healthy stomach killed the micro-organism ; 

 (2) that even when it found its way into the intestine, it was 

 passed along it so rapidly that it could not take any effect on 

 the healthy or even slightly irritated mucous membrane, or 

 that it was actually very rapidly destroyed in the intestine 

 itself. In guinea pigs, in which he attempted to produce 

 cholera, he found that there was great acidity of the gastric 

 juice, and that the peristaltic movements of the intestine 

 were very strong and rapid. 



It will have been concluded from what has been stated 

 that both naturally and in artificial cultivations there is 

 some poison developed during the growth of the bacillus, 

 which, when introduced in considerable quantities, produces 



