408 BACTERIOLOGY. 



typical pathological changes have regularly followed 

 animal inoculations, but in most cases they could easily 

 be traced to the toxaemia produced by the substances in 

 the bodies of the bacilli injected, not necessarily accom- 

 panied by the growth of the organism, rather than to 

 infection due to the development of the typhoid bacillus 

 in the tissues. 



In a certain number of cases subcutaneous and intra- 

 peritoneal inoculations in animals have been productive 

 of more or less typical typhoid lesions. Among the 

 most successful efforts in this direction are the experi- 

 ments of Cygnaeus and Seitz, who, by the inoculation 

 of the typhoid bacillus into dogs, rabbits, and mice, 

 produced in the small intestines conditions that were 

 histologically and to the naked eye analogous to those 

 found in the human subject, but their results were not 

 constant. Of a number of experiments made by Ab- 

 bott, 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 iden- 

 tical with those found at autopsy in the small intestines 

 of the human subject dead of this disease. The bacilli 

 were found in the spleen. 



Experiments indicate that the presence of other bac- 

 teria in the body, and of exposure to the effect of nox- 

 ious gases in lowering the natural resistance of the 

 individual, render him more susceptible to infection 

 from typhoid fever and, indeed, from other infectious 

 diseases. 



But whatever conclusions may be drawn from these 

 results, with regard to the typhoid process in animals, 

 typhoid fever in the human subject is now recognized 



