TYPHOID FEVER 137 



dependently by Koch. That it is the veritable germ 

 of the infectious disease known as typhoid fever has 

 been demonstrated by subsequent researches and is 

 now generally admitted. This bacillus grows readily 

 in milk, in beef tea, and in other culture media usually 

 employed by bacteriologists. It is killed by a few 

 minutes' exposure to a temperature of 140 Fahr. 

 (60 C.), but unlike the cholera spirillum is not readily 

 destroyed by desiccation, having been preserved in 

 dry and pulverised soil for a period of twenty-five 

 days. It may preserve its vitality in sterilised water 

 for four weeks or more, and in typhoid excreta for at 

 least three months. It has been recovered by culti- 

 vation from earth, upon which bouillon cultures had 

 been poured, after an interval of five and one-half 

 months ; and from soil which had been manured 

 with the undisinfected discharges of typhoid patients 

 after these discharges had remained in a pit during 

 five winter months. 



These facts make it apparent why typhoid fever 

 has become so widely disseminated throughout the 

 world and why it is the principal endemic filth disease 

 in the United States. A primitive and sparse popula- 

 tion, which obtains its drinking water chiefly from 

 live springs and running streams, is less liable to 

 suffer from this disease than the permanent denizens 

 of towns which are destitute of sewers and which 



