384 Profs. Percy Frankland and Marshall Ward. 



Quantitative Analysis of Thames Water in December. 



Oil December 27, 1893, a cloudy and misty cold morning following 

 on a series of bright sunny cold days, a sample of Thames water was 

 taken at 11 A.M., and immediately conveyed to the laboratory, and 

 plates made as follows. The water on collection was at nearly 

 '8 C. 



Twenty-two plates in all were made, of which twelve were in- 

 cubated at 8 12 C., the temperature of the laboratory, and ten at 

 18 20 C. in the incubator. There were a good many changes of 

 temperature from day to day in the case of the former, though but 

 slight and slow alterations in the latter case. 



The following tables give the results of the plate cultures, every 

 colony visible with the hand lens being counted each day as before ; 

 and this time the low temperature cultures were continued for 

 240 hours (ten days), in order to see how far the numbers would 

 eventually approximate to those of the higher temperature plates. 



An innovation was made in the case of the plates marked R^I^, 

 S^, TiTa. Here I used 1 drop of the Thames water between each 

 pair of plates. The drop was allowed to fall as usual into the tube 

 of gelatine, then a second tube of sterile gelatine emptied into the 

 infected tube ; then the contents were distributed rapidly into two 

 plates, the countings of which must be taken together as is done in 

 the table. It is noteworthy how much higher the final numbers are 

 in these plates as compared with others, no doubt chiefly owing to 

 the more complete separation of the bacteria from which the colonies 

 arise, and to their having more space to develope in. 



