CHOLERA AGGLUTINATION 533 



confirm Koch's work. The organism is found in all cases 

 of cholera, and a few instances of laboratory infection 

 from cultures have been recorded. 



None of the lower animals suffers from or contracts a 

 disease in any way comparable to Asiatic cholera, so that 

 the test of animal experiment cannot be applied except 

 in the case of young suckling rabbits (see below, " Anti- 

 serum "). By first neutralising the acidity of the gastric 

 juice by an injection of sodium carbonate solution into 

 the stomach, then diminishing peristalsis by an injection 

 of tincture of opium into the peritoneal cavity, and finally 

 injecting a broth culture of the cholera vibrio into the 

 stomach, Koch succeeded in inducing in guinea-pigs a 

 condition somewhat similar to cholera in man namely, 

 indisposition with falling temperature, weakness of the 

 extremities, and death in forty-eight hours. Post mortem, 

 the small intestine was congested and filled with a watery 

 fluid containing large numbers of the vibrios. Injected 

 into the peritoneal cavity of mice, guinea-pigs and rabbits, 

 the vibrio produces death from a general septicaemia. 

 The vibrio is only slightly, if at all, pathogenic for pigeons 

 by intra-muscular inoculation. The virulence varies much 

 and is lost under cultivation. 



Metchnikoff ascribed the immunity of animals to intes- 

 tinal cholera as largely due to the inhibitory action of 

 the other organisms present in the digestive tract. In 

 man digestive disturbances are often an important 

 predisposing cause of an attack. The acidity of the 

 gastric juice is also probably a means of defence (see 

 "Water"). 



The blood-serum of an animal immunised by injections 

 of the cholera vibrio gives a typical agglutination reaction 

 with recent cultures of the organism. The reaction can 

 also be obtained with the serum-blood of cholera patients. 



According to Greig, in non-fatal cases the cholera 



