70 



disappeared at the end of 34 days in unsterilised Thames 

 water and that there was no multipHcation in potable 

 water. Observations thus tend to show that neither 

 sewage nor fresh water are favourable media and that the 

 former is the least favourable. 



A further very important point is the action of salt 

 water upon the typhoid bacillus. In 1889 Giaxa made 

 observations upon the vitality of the B. typhosus in 

 sterilised and unsterilised sea water and showed that it 

 was present in the latter up to the 9th day, and in the 

 former to the 25th. Frankland and Ward showed that a 

 3 % salt solution most prejudicially influences the growth 

 of the Bacillus, the latter disappearing by the 18th day. 



Our own experiments have been made so far with 

 sterilised sea water incubated at 35*^0., and in one case 

 at 8° — 10°C. A culture of the B. typhosus on agar was 

 emulsified with sterilised water and a definite quantity of 

 this in each instance was added to the sterilised sea water. 

 Experiment I. No. of bacilli at time of mixing 29,250. 

 After 21 hours 20,475. 



45 



71 



95 



271 



340 



9,945. 



9,360. 



5,850. 



260. 



11. 



Experiment II. At time of mixing 1,300. 



After 21 hours 1,105. 



45 



71 



95 



271 



340 



780. 

 650. 

 325. 



2. 



0. 



Experiment III. At time of mixing 22,750. 



After 5 hours 17,550. 



