544 Profs. Percy Fraiikland and Marshall Ward. 



amount to that in Thames water, but almost exclusively derived from 

 vegetable sources (peat) ; or, again, other upland surface water much 

 more highly impregnated with peaty matter ; or, lastly, deep well 

 water containing the merest traces of organic matter, was employed. 

 In all cases, of course, special precautions were taken to prevent, 

 as far as possible, the importation of culture- material along with the 

 bacilli. 



2. By first submitting the typhoid bacilli to prolonged culture in 

 more and more aqueous media, and then introducing them into 

 steam-sterilised Thames water, slight but distinct multiplication of 

 the typhoid bacilli was observed, and, although, perhaps, by this 

 method of training the typhoid bacilli had become more adapted to 

 aquatic life, it appears probable that the multiplication observed took 

 place at the expense of the minute quantity of culture-material neces- 

 sarily introduced with them ; for on transferring some of this infected 

 water in which multiplication had taken place to a larger volume of 

 the same steam-sterilised Thames water, no further multiplication 

 was found to occur, showing that the organic matter belonging to the 

 steam-sterilised Thames water itself was not capable of ministering to 

 the growth and proliferation even of these specially educated typhoid 

 bacilli. 



3. Although no instance of multiplication of the introduced typhoid 

 bacilli in these steam-sterilised potable waters was observed, on the 

 other hand the bacilli were found to be possessed of very considerable 

 longevity in them, thus : 



Description of steam-sterilised water. 



Thames water (11.5.1893) kept at 6 8C. 



. 19 C. 



Loch Katrine water (4.7.1893) kept at 



68 C. 



Duration of life of typhoid bacillus. 



Upwards of 76 days! Still just recognis- 



J able. 



Upwards of 21 "I Only a small number of 

 days I typhoid bacilli was in- 



Loch Katrine water (4.7.1893) kept at ! Between 13 f troduced into these 



19 C. 

 Thames water (19.10.1893) kept at 



912 C. 

 Loch Katrine water (19.10.1893) kept at 



912 C. 

 Deep well water (19.10.1893) kept at 



912 C. 

 Thames water (16.1.1894) kept at 



912 C. 

 Peaty upland surface water (17.10.1893) 



kept at 912 C. 



and 17 days J waters. 



Between 32^ Typhoid bacilli from 



and 39 days j one and the same 



Upwards of 51 ! source and in the same 



days j numbers were intro- 



Between 20 j duced into each of 



and 32 days J these waters. 



Upwards of 48 days (still abundantly 



present) . 



Upwards of 24 days (still abundantly 



present). 



In no case was the duration of vitality a very limited one ; its 

 exact length in any particular water is doubtless dependent on the 

 initial vitality of the bacilli and the numbers in which they are 

 introduced. In the strictly comparative experiment on steam- 

 sterilised Thames, Loch Katrine, and deep well water, it is seen that 

 the longevity of the typhoid bacillus is distinctly greatest in the Loch 



