124 THE BACTERIA IN ASIATIC CHOLERA. [CH. 



" In these experiments it struck me that, the better the 

 operation was performed, and the less extensive the manipu- 

 lations, the less chance was there of the animals dying of 

 cholera;" and further "in this set of experiments also (with- 

 out ligature of the bile-duct) the results are so much the less 

 positive the less disturbance and the less the intestine is 

 squeezed or torn in searching for and pulling forward the 

 duodenum. Hence the experiment succeeds only excep- 

 tionally, when one limits oneself to opening the abdominal 

 cavity only to a small extent, and making the injection into 

 the coil of intestine first exposed, instead of into the deep- 

 lying duodenum. Of six guinea-pigs which were operated 

 on in this way, only one died of cholera, the rest remained 

 alive. The same experiment was then performed on three 

 rabbits, without any of them dying or even becoming ill." 



Well, by these experiments Koch thought himself quite 

 justified in refusing von Pettenkofer's challenge; he said, 

 " Under these circumstances it is more advisable to decline 

 the offer of those persons who recently proposed to swallow 

 pure cultivations of comma-bacilli, and for the present to 

 continue the experiments on guinea-pigs and other animals." 



The most exact and carefully-conducted experiments have 

 been made by van Ermengem, and they contrast, as to care 

 and precision and number, as well as in the character of the 

 experiments, with those published by Babes, Doyen, 

 Watson Cheyne, and others. I shall therefore for the 

 present refer only to the experiments of van Ermengem. 

 The most noteworthy result made known by him is this, 

 that guinea-pigs inoculated per duodenum with relatively 

 large doses of choleraic comma-bacilli cultivated in serum 

 (one gramme to half a gramme) died in the course of between 

 two and eighteen hours. The symptoms presented by these 

 animals were those of acute chemical poisoning, for what 



