EXPERIMENTAL PATHOLOGY. 



335 



appeared about the sixth day, and the contamination of the food 

 was then stopped. The illness which followed was characterised 

 by general weakness, diarrhoea, and pyrexia (the temperature 

 curve being of the nature of that seen in human typhoid), and the 

 agglutination reaction (vide infra] was obtained. In some cases 

 recovery took place after eight to twelve days' illness ; sometimes 

 death after twelve to eighteen days. Post mortem there was 

 observed congestion of the small intestine, especially of the last 

 part, and of Peyer's patches, enlargement of mesenteric glands 

 and spleen, and in the latter typhoid bacilli were present. The 

 blood was sterile. The chief objection which can be urged against 

 these experiments is that they were performed in the rabbit 

 an animal very liable to be affected by pathogenic agents in 

 peculiar ways. 



While feeding experiments are thus rather unsatisfactory, 

 the same may be said of the results of subcutaneous or intraperi- 

 toneal infection. Here, again, pathogenic effects can easily be 

 produced by the typhoid bacillus, but these effects are of the 

 nature of a short acute illness characterised by pyrexia, rapid 

 loss of weight, inability to take food, and frequently ending 

 fatally in from twenty-four to forty-eight hours. The type of 

 disease is thus very different from what occurs naturally in man. 

 In such injection experiments the results vary considerably, 

 sometimes scarcely any effect being produced by a large dose of 

 a culture. This is no doubt due to the fact that different cases 

 of the bacillus vary much in virulence. Ordinary laboratory 

 cultures are often almost non-pathogenic. They can, however, 

 be made virulent in various ways. This Chantemesse and 

 Widal effected by injecting along with the typhoid culture the 

 sterilised products of the streptococcus pyogenes, and Sanarelli 

 used for the same purpose sterilised cultures of the B. coli, 

 which were injected intraperitoneally at the same time as a 

 typhoid bacillus was introduced subcutaneously. After this 

 procedure had been repeated through a series of animals, a 

 culture of typhoid was obtained of exalted virulence. Sidney 

 Martin has obtained virulent cultures by passing bacilli, derived 

 directly from the spleen of a person dead of typhoid fever, 

 through the peritoneal cavities of a series of guinea-pigs. 



Sanarelli, studying the effects of the intraperitoneal injection 

 of a few drops of a culture of highly exalted virulence, found 



