Report on the Bacteriology of Water. 



243 



had taken place during the seven months' residence in the water, yet 

 sufficient remained even then to be discoverable by cultivation, and 

 to prove fatal to mice when 1 c.c. of the water was subcutaneously 

 injected into them. Only in one instance did a mouse remain alive 

 after receiving such an injection, and on repeating the experiment, 

 the second mouse injected with the same water duly died of anthrax 

 (pp. 214—219). 



5. In the unsterilised Loch Katrine water, the behaviour of the 

 anthrax spores was particularly remarkable. At the commencement 

 of the experiment there were about 5000 anthrax germs and 500 

 other micro-organisms per cubic centimetre. These micro-organisms 

 underwent, as was to be anticipated, very large multiplication, 

 especially in that portion of the water which was kept at a summer- 

 temperature. Fourteen days after the commencement of the experi- 

 ment cultivation still showed the anthrax to be abundant, but their 

 number was markedly greater in that portion of the water which had 

 been kept at winter than in that kept at summer temperature (p. 229). 



On re- examination 3 months after the beginning of the experi- 

 ment, the anthrax was absolutely undiscoverable by cultivation in 

 the water kept at summer temperature, whilst it was still present in 

 considerable, although greatly diminished numbers, in the water 

 which had been kept at the lower temperature (p. 230). 



The same difference was observed ir respect of virulence also, for 

 in every case mice injected with the low temperature water died of 

 anthrax, whilst those which received the same quantity of the higher 

 temperature water remained alive. Indeed it was not until broth 

 was added to this water kept at summer temperature that, of two 

 flasks so treated, the one became virulent, whilst the other still 

 remained innocuous (pp. 236 — 238) = 



It should be mentioned also that in this Loch Katrine water kept 

 at the higher temperature (18° C.) the ordinary water bacteria 

 became very much diminished in number after the preliminary multi- 

 plication referred to above (pp. 226, 227). 



This remarkable bactericidal power of the unsterilised Loch Katrine 

 water kept at 18° C. is doubtless due to the elaboration by the water 

 bacteria of toxic products from the peaty organic matter present in 

 this water, which products cause the destruction either of the spores 

 or of the bacilli into which the anthrax spores will at this tempera- 

 ture gradually germinate. Moreover, the difference in this respect 

 between the Thames water and that of Loch Katrine is to be sought 

 for in the different nature of the organic matter present in these 

 waters. The analyses show that quantitatively the organic matter (as 

 measured by organic carbon and nitrogen) in both waters is almost 

 exactly the same, but qualitatively they are very different, that in the 

 Loch Katrine water being much less oxidised than that in Thames 



