Report on the Bacteriology of Water. 

 Bottle Screens, Coloured, &c. 



331 



Results. 



Bemarks. 



Good letter W , 



Nothing appeared on the plate 

 till the third day, and then 

 only about 200 colonies at 

 the extreme margin. No 

 letter in six days 



No letter in six days 



No trace of germination any- 

 where on the plate, except 

 extreme margin 



Excellent sharp letter N 



Letter T visible after eighteen 

 hours incubation, but not 

 sharp 



No letter C. Germination took 

 place equally all over the 

 plate 



Letter Y feebly visible after 

 twenty-four hours 



No letter X. Germination 



equal all over plate 

 Sharp letter Z. 



No trace of letter. 



Extremely faint B. 

 No letter. 



No trace of letter. 



Faint letter C. 



No trace of letter. 



Very faint letter X , 

 YOL. LVI. 



The first three days showed powerful inhibition- 

 effects, and no letter was visible till fourth day : 

 then sharp and clear. 



From 20th to 25th the weather was dull and cold. 

 Temperature of plates averaged 6 C., and none 

 had germinated on morning of 25th, when we 

 had brilliant hot sunshine. 



The letter after three days was not very sharp, 

 since the colonies around were large and not very 

 numerous, and about six or eight were seen on 

 the insulated area. 



Even on the fourth day the contrast was not sharp, 

 the surrounding colonies being so few and so 

 large. 



Closer inspection showed a faint " ghost " of letter 

 X on third day. 



*The chlorophyll at first (Feb. 26) blocked out all 

 the blue-violet, and had bands in red and green ; 

 but during the last two hours (Feb. 28) it only 

 cut off violet, and had feeble bands in red and 

 green. Colour olive, in place of deep blue-green. 



*The chlorophyll = deepest solution ; total ab- 

 sorption from b onwards, and deep broad bands 

 in red and green. 



Temperature rather high. Sun very bright and 

 hot, but interrupted by clouds occasionally. 

 The exposures began before 2 P.M., and ended 

 just after 4 P.M., and two hours expresses the 

 maximum of sunlight. All were over plane 

 mirrors, carefully adjusted. 



The experiment was of little value. I had probably 



not used a sufficiently large charge of spores. 

 These dilute fuchsin screens need careful watching. 



The colouring matter gathers it to flocks in time, 



and lets much more light through. 

 2 A 



