Report on the Bacteriology of Water. 



369 



A, culture cell (quartz floor, &c.) arranged as usual ; B, an inverted matchbox 

 painted black and with a hole over the hanging drop ; C, a quartz bottle screen of 

 water or bichromate, placed over the hole, so that no light can reach the hanging 

 drop except through the screen. 



and support the (quartz) screen. Each stood side by side, with a 

 dummy cell provided with a thermometer, one pair (culture and 

 dummy) under bichromate, the other under water. 



They were on a table outside the north laboratory, exposed to the 

 blue sky, but with no trace of direct sunlight. The amount of white 

 cloud increased from 10.45 to 11.15, and very little open sky was 

 available, except at intervals. The details concerning temperature 

 and weather are given in the following table : 



At 7 P.M. all were brought into the laboratory, and the tempera- 

 ture rose to 16-25 at 7.5, 18 at 7.20, 18 at 8.45. 



