578 BACTERIOLOGY. 



over, that the comma bacillus is extremely sensitive to 

 the action of acids, and is quickly destroyed by the acid 

 secretions of the stomach of man or the lower animals 

 when these secretions are normally produced. Despite 

 the small prospects of success, however, from animal 

 experiments, these have been undertaken again and 

 again, until finally a method was found by which at 

 least similar processes have been produced in test ani- 

 mals by inoculation of pure cultures of the cholera 

 vibrio. Koch sought to produce infection in guinea- 

 pigs per vias naturales by first neutralizing the con- 

 tents of the stomach with a solution of carbonate of 

 soda 5 c.c. of a 5 per cent, solution injected into the 

 stomach through a pharyngeal catheter and then after 

 a while administered through a similar catheter 10 c.c. 

 of a liquid into which had been put one or two drops 

 of a bouillon culture of the comma bacillus. The ani- 

 mal then receives a dose of 1 c.c. of tincture of opium 

 per 200 grammes of body-weight introduced into the 

 abdominal cavity, for the purpose of controlling the 

 peristaltic movements. As a result of this treatment 

 the animals are completely narcotized for about half an 

 hour, but recover from it without showing any ill effects. 

 On the evening of the same or following day the ani- 

 mal shows an indisposition to eat and other signs of 

 weakness, its posterior extremities become weak and 

 apparently paralyzed, and, as a rule, death occurs 

 within forty-eight hours with the symptoms of collapse 

 and fall of temperature. At the autopsy the small 

 intestine is found to be congested and filled with a 

 watery fluid containing the spirillum in great numbers. 

 Koch experimented in this way on about one hundred 

 guinea-pigs. These results, however, are somewhat 



