172 ASIATIC CHOLERA. 



Artificial Susceptibility. A number of ingenious devices 

 have been resorted to to render animals susceptible to inocula- 

 tion of the comma bacillus. 



The method of Koch is ingenious and very successful. It 

 consists in neutralizing the acidity of the gastric juice in a 

 guinea-pig by the inoculation of 10 c.c. of a 5 per cent, 

 solution of carbonate of sodium. This is introduced into the 

 stomach by means of a soft catheter. A few minutes after- 

 ward 10 c.c. of young bouillon cultures of the cholera spiril- 

 lum are introduced also into the stomach through the same 

 catheter, and immediately an intraperitoneal injection of 1 c.c. 

 of laudanum is made into the animal, for the purpose of retard- 

 ing peristaltic action. The animal for an hour or so remains 

 in a stupefied condition from the action of the opiate, but it 

 soon revives. It shows, however, a complete loss of appetite, 

 and at the end of twenty-four hours begins to show signs of 

 paralysis of the hind extremities, with coldness of the sur- 

 face. This paralysis gradually increases until in forty-eight 

 hours the animal dies, showing pathologically some lesions 

 resembling those found in man in cases of cholera i. e., a 

 large amount of white serous exudate in the intestinal canal, 

 with intense congestion of the intestines. Pure colonies of 

 the spirillum may be obtained from these secretions. 



Intraperitoneal injections in animals are followed by death 

 in two or three hours. The symptoms are those of a rapid 

 and intense peritonitis. 



Immunity. When the injections into animals are made in 

 quantities too small to produce death the animal is protected 

 for a time from subsequent fatal doses, and its serum has 

 been found useful to protect animals of the same species 

 against inoculations with fatal doses of the bacteria. 



The blood-serum of these immunized animals, as well as 

 that of cholera patients, has been found in a dilution of 1 to 

 50 to possess the power of agglutination when mixed with 

 young bouillon cultures of the bacteria. This may be used 

 as a diagnostic test of the disease. 



The organism is seldom or never found in the general cir- 

 culation nor in the internal organs of cholera cases. 



