EXPERIMENTAL INOCULATION. 413 



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 multi- 

 plication 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 produc- 

 ing, 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. Thinking 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. Of nineteen animals treated in this way, only one 

 died with choleraic changes in the small intestine. This animal had 

 aborted a short time previously, and as its abdominal walls were very 

 relaxed, Koch considered that the intestinal peristalsis had* been 

 interfered with, and thus opportunity had been afforded to the organ- 

 isms of gaining a foothold and multiplying in the intestine. He 

 accordingly tried the effect of artificially interfering with the intestinal 

 peristalsis by injecting tincture of opium into the peritoneum (i c.c. 

 per 200 grm. weight), in addition to neutralising as before with the 

 carbonate of sodium solution. The result was remarkable, as thirty, 

 out of thirty-five animals treated, died with the same changes as in the 

 single animal in the previous series of experiments. 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 colourless fluid 

 with small flocculi and the cholera Organisms in practically pure cultures. 

 There experiments, which have been repeatedly confirmed, therefore 

 demonstrated that the cholera organisms could, under certain con- 

 ditions, 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 



