PATHOGENIC EFFECTS OF B. TYPHOSUS 365 



strated in chronic suppurations occurring in the gall-bladder. 

 It is to be noted that gallstones are more frequently found in 

 women than in men, the proportion being about four to one, 

 and probably a considerable proportion of the total number of 

 cases of gallstones are traceable to the previous occurrence of 

 typhoid fever. 



Pathogenic Effects produced in Animals by the Typhoid 

 Bacillus. There is no disease of animals which can be said 

 to be identical with typhoid, nor is there any evidence of the 

 occurrence of the typhoid bacillus under ordinary pathological 

 conditions in the bodies of animals. Attempts to communicate 

 the disease to animals by feeding them on typhoid dejecta have 

 been unsuccessful, and though pathogenic effects have been 

 produced by introducing pure cultures in food, the disease has 

 usually borne no resemblance to human typhoid. The most 

 successful experiments have been those of Remlinger, who, by 

 continuously feeding rabbits on vegetables soaked in water con- 

 taining typhoid bacilli, produced in certain cases symptoms 

 resembling those of typhoid fever (diarrhrea, remittent pyrexia, 

 etc.). An agglutinating action was observed in the serum, and 

 post mortem there was congestion of the Peyer's patches, and 

 typhoid bacilli were isolated from the spleen. 



Feeding experiments are thus unsatisfactory, and the same 

 may be said of the results of subcutaneous or intraperitoneal 

 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 strains of the 

 bacillus vary much in virulence. Ordinary laboratory cultures 

 are often almost non-pathogenic. They can, however, be made 

 virulent in various ways. Sanarelli used the method of injecting 

 sterilised cultures of the b. coli intraperitoneally at the same 

 time as the typhoid bacillus was introduced subcutaneously. 

 After this procedure had been repeated through a series of 

 animals, a typhoid culture of exalted virulence was obtained. 

 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 



