TYPHOID INOCULATION IN ANIMALS. 229 



truly infective^ action of the materials introduced into 

 the animals. 



The most successful efforts for the production of 

 the typical typhoid lesions in lower animals are those 

 recently reported by Cygnseus. By the introduction 

 of the typhoid bacilli into the tissues of dogs, rabbits, 

 and mice he was able to produce in the small intestines 

 conditions which were histologically and to the naked 

 eye analogous to those found in the human subject. 



Of a number of experiments made by the writer 

 with the same object in view, only one positive result 

 followed the introduction of typhoid bacilli into the 

 circulation of rabbits. In this case the ulcer in the 

 ileum was macroscopically and microscopically identical 

 with those found at autopsy in the small intestine of 

 the human subject dead of this disease. The typhoid 

 bacilli were not only obtained from the spleen of the 

 animal by culture methods, but were also demonstrated 

 microscopically in their characteristic clumps in sections 

 of the organ. 



Because of the variations in the morphology and cul- 

 tural peculiarities of this organism, and because of the 

 difficulty experienced in efforts to reproduce in lower 

 animals the conditions found in the human subject, 

 typhoid fever is bacteriologically one of the most un- 

 satisfactory of the infectious diseases. 



There are a number of other organisms which botani- 

 cally appear to be so closely related to the typhoid bacil- 

 lus, and which, with our present methods for studying 

 these organisms, so closely simulate it, that the difficulty 



1 Infective or septic — poisoning of the tissues as a result of the 

 growth of bacteria in them. 



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