480 Profs. Percy Fraukland and Marshall Ward. 



Thus again in the LocJi Katrine water, sterilised by filtration througTa 

 porous porcelain, the typhoid bacilli underwent rapid degeneration, 

 more especially in the water which was preserved at the summer tempera- 

 ture, in which they were no longer found by plate cultivation twenty-one 

 days after infection, whilst in the same water Icept at the winter tempera- 

 ture they were still easily recognisable, althoiigh in greatly diminished 

 numbers, on that day. 



It is particularly noteworthy that the behaviour of the typhoid bacilli 

 was practically identical in this Loch Katrine water, irrespectively of 

 whether it was employed in the unsterilised or in the sterilised condition, 

 and irrespectively of whether the sterilisation was effected by steam or by 

 filtration through porous porcelain. 



In all cases, 'moreover, the effect of temperature on the typhoid bacillus 

 was very marlced, the longevity being much greater in the Loch Katrine 

 water, unsterilised or sterilised, Jcept at the ivinter than in that kept at the 

 summer temperature. 



The behaviour of the B. coli communis in these sterilised L. Katrine 

 waters is recorded in the following tables : 



