244 Profs. Percy Frankland and Marshall Ward. 



water, as measured by the oxygen which they respectively absorb from 

 permanganate. This doubtless means that the Loch Katrine organic 

 matter has hitherto been a comparative stranger to bacterial life, 

 whilst the organic matter of the Thames has been more fully ex- 

 ploited by the micro-organisms which are more abundant in its 

 waters. It is evident, however, that the Loch Katrine organic matter 

 per se is not possessed of bactericidal powers at the higher tempera- 

 ture, for in the sterilised Loch Katrine waters at that temperature the 

 anthrax spores underwent no such destruction (pp. 182, 227, 232 

 —235, 238). 



