BACILLUS TYPHOSUS. 413 



Not only do the very great majority of cases exam- 

 ined bacteriologically and pathologically, but the epi- 

 demiological history of the disease, prove that the 

 chief mode of invasion of the typhoid bacillus is by 

 way of the mouth and stomach. The infective mate- 

 rial is discharged principally by means of the excretions 

 and secretions of. the sick namely, by the feces, the 

 urine, and occasionally by the sputum. 



Of considerable practical importance is it to know for 

 what length of time the typhoid bacillus is capable of 

 living outside of the body; but, unfortunately, owing 

 to the great difficulties in proving the presence of this 

 organism in natural conditions, our knowledge on this 

 point is very deficient. In feces the length of life of 

 the typhoid bacilli is very variable; sometimes they 

 live but a few hours, usually a few days, exceptionally 

 for very long periods. Thus, according to Uffelmann, 

 typhoid bacilli may remain alive in feces for five and 

 a half months, and, according to Karlinski, for at least 

 several months. Foote says that they can be found in 

 living oysters for a month at a time. Their life in 

 feces and in water, however, is usually very much 

 shorter. As a rule, they can be detected in water no 

 longer than fourteen days after introduction. The 

 life of the typhoid bacillus varies according to the 

 abundance and varieties of the bacteria associated with 

 it and according to the presence or absence of such in- 

 jurious influences as high temperature, light, desicca- 

 tion, etc., to which it is peculiarly sensitive. That the 

 bacilli do live much longer under favorable circum- 

 stances, as to protection and nourishment, than is gen- 

 erally supposed, is shown by the fact, as reported by 

 Buschke, that they were found in an old bone-centre 



