EXPERIMENTAL INOCULATION 407 



experiments on animals by feeding them with pure cultures were 

 attended with negative results. As the organisms are confined 

 to the alimentary tract in the natural disease, attempts to induce 

 their multiplication within the intestine of animals by artificially 

 arranging favouring conditions, have occupied a prominent place 

 in the experimental work. We shall give a short account of 

 such experiments. 



Nikati and Rietsch were the first to inject the organisms directly into 

 the duodenum of dogs and rabbits, and they succeeded in producing, in 

 a considerable proportion of the animals, a choleraic condition of the 

 intestine ; in their earlier experiments the common bile duct was 

 ligatured, but the later were performed without this operation. These 

 experiments were confirmed by other observers, including Koch. Think- 

 ing that probably the spirillum, when introduced by the mouth, is 

 destroyed by the action of the hydrochloric acid of the gastric secretion, 

 Koch first neutralised this acidity by administering to guinea-pigs 5 c.c. 

 of a 5 per cent solution of carbonate of soda, and sometime afterwards 

 introduced a pure culture into the stomach by means of a tube. As this 

 method failed to give positive results he tried the effect of artificially 

 interfering with the intestinal peristalsis by injecting tincture of opium 

 into the peritoneum (1 c.c. per 200 grm. weight), in addition to neutral- 

 ising as before with the carbonate of sodium solution. The result was 

 remarkable, as thirty out of thirty -five animals treated died. The 

 animals infected by this method show signs of general prostration, their 

 posterior extremities being especially weakened ; the abdomen becomes 

 tumid, respiration slow, heart's action weak, and the surface cold. 

 Death occurs after a few hours. Post mortem the small intestine is 

 distended, its mucous membrane congested, and it contains a coiourless 

 fluid with small fiocculi and the cholera organisms in practically pure 

 cultures. These experiments, which have been repeatedly confirmed, 

 therefore demonstrated that the cholera organisms could, under certain 

 conditions, set up in animals a condition in some respects resembling 

 cholera. Koch, however, found that when the spirilla of Finkler and 

 Prior, of Deneke, and of Miller (vide infra), were employed by the same 

 method, a certain, though much smaller, proportion of the animals died 

 from an intestinal infection. Though the changes in these cases were 

 not so characteristic, they were sufficient to prevent the results obtained 

 with the cholera organism from being used as a demonstration of the 

 specific relation of the latter to the disease. 



Within later years some additional facts of high interest have been 

 established with regard to choleraic infection of animals. For example, 

 Sabolotny found that in the marmot an intestinal infection readily takes 

 place by simple feeding with the organism, there resulting the usual 

 intestinal changes, sometimes with hsemorrhagic peritonitis, the organ- 

 isms, however, being present also in the blood. It was found by Issaeff 

 and Kolle that young rabbits could be infected by merely neutralising 

 the gastric secretion with sodium carbonate, the use of opium being 

 unnecessary ; but of special interest is the fact, discovered by Metchnikoff, 

 that in the case of young rabbits shortly after birth a large proportion 

 die of choleraic infection when the organisms are simply introduced 

 along with the milk, as may be done by infecting the teats of the 

 mother. Further, from these animals thus infected the disease may be 



