332 TYPHOID FEVER 



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 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 

 that the Peyer's patches and solitary glands of the intestine 

 were enormously infiltrated, sometimes almost purulent, and 

 that they contained typhoid bacilli, as also did the mesenteric 

 lymphatics and glands, and the spleen. These results are 

 interesting, but have not been confirmed. 



The Toxic Products of the Typhoid Bacillus. Here very 

 little light has been thrown on the pathology of the disease, but 

 the general results may be outlined. We may state that there 

 exist in the bodies of typhoid bacilli toxic substances, that in 

 artificial cultures these do not pass to any great degree out into 

 the surrounding medium, and that though they produce effects on 

 the intestine, there is evidence that such effects are not character- 

 istic and not peculiar to the toxins of the b. typhosus. Sidney 

 Martin found that the bodies of bacteria killed by chloro- 

 form vapour were very toxic, more so than filtered cultures. 

 Diarrhoea was a constant symptom after injection, but no change 

 in the Peyerian patches was observed. Martin found that 

 virulent cultures of the b. coli gave similar results when 

 similarly treated. Allan Macfadyen, by grinding up typhoid 

 bacilli frozen solid by liquid air, produced a fluid whose toxic 

 effect he attributed to the presence of the intracellular poisons. 



The Immunisation of Animals against the Typhoid 

 Bacillus. Earlier observers had been successful in accustoming 

 mice to the typhoid bacillus by the successive injections of small 

 and gradually increasing doses of living cultures of the bacillus. 

 Later, Brieger, Kitasato, and Wassermann found that the bacillus 

 when modified by being grown in a bouillon made from an 

 extract of the thymus gland no longer killed mice and guinea- 

 pigs These animals after injection were moreover immune, and 

 it was also found that the serum of a guinea-pig thus immunised 

 could, if transferred to another guinea-pig, protect the latter 

 from the subsequent injection of a dose of typhoid bacilli to 



