424 A MANUAL OF BACTERIOLOGY 



we have little certain information ; probably it tends to 

 die out within a few days. In sterilised sewage inoculated 

 with it the B. typhosus hardly multiplies at all, and 

 at the end of ten days dies out. Certain organisms 

 in sewage seem to have a deleterious action on the 

 B. typhosus, hastening its extinction, viz. the B. fluorescens 

 hquefaciens and B. fluorescens stercoralis. Russell and 

 Fuller, subjecting the bacillus to the direct action of 

 sewage, found the survival to range from three to five 

 days. 



In dry garden earth the Bacillus typhosus may be 

 recovered up to twenty -five days ; in peat it dies out 

 within twenty -four hours. In moist soil it may survive 

 for more than six weeks ; in artificially dried soil it dies 

 out by the seventh day. 



Sidney Martin found that in moist sterilised soil inocu- 

 lated with a broth culture and kept at temperatures from 

 3 to 37 C., the B. typhosus maintains its vitality for 

 upwards of fifteen months, but that in un sterilised soil 

 it rapidly dies. 1 



Mair 2 concludes that the typhoid bacillus can survive 

 in natural soil in large numbers for about twenty days, and 

 is still present in a living condition after seventy to eighty 

 days, but that there is no evidence that it is capable of 

 multiplying and leading a saprophytic existence in ordi- 

 nary soil. He suggests that the rapid death of the 

 bacillus in unsterilised soil in Martin's experiments was 

 due to the use of broth cultures for infection, the 

 broth added causing a multiplication of the saprophytes. 

 Firth and Horrocks 3 similarly conclude that the typhoid 

 bacillus displays no tendency to increase in numbers, nor 

 to grow upwards or downwards in soil, though it may be 



1 Reps. Med. Off. LOG. Gov. Board for 1896-1901. 



2 Journ. of Hygiene, vol. viii, 1908, p. 37. 



3 Brit. Med. Journ., 1902, vol. ii, p. 936. 



