

Report on the Bacteriology of Water. 



350 



XVIII. 



On August 20, two Erlenmeyer flasks, labelled F! and F 2 , were 

 charged to a depth of about an inch with sterile-distilled water with 

 which a loopf ul of spores of B. anthracis had been thoroughly shaken 

 up. Flask FI was exposed with a mirror below and one behind ; F 2 

 was wrapped in foil and black paper. 



The exposure was from 11.30 A.M. to 5 P.M., but it was a windy 

 and cloudy day, with a good deal of rain. Just before exposure, two 

 plates were made to determine the number of spores introduced per 

 c.c. in the flask F t . One plate gave 1,950,000, and the other 

 2,445,000 ; total, 4,395,000 ; mean, 2,197,500 per c.c. 



Two plates from F 2 gave respectively 2,052,000 and 2,280,000; 

 total, 4,332,000; mean, 2,166,000. 



Or, if we take the average of the four plates, we get total = 

 8,727,000; average of the four = 2,181,750; and it will be noticed 

 how well the four plates agreed. 



At 5.30 P.M. two plates were made from the covered flask, and gave 

 per c.c. 1,700,000 and 340,000 respectively. It was noted, however, 

 that the second plate had been badly levelled, and the colonies were 

 heaped up to one side, and could not be properly estimated. Taking 

 the numbers as they stand, we get total = 2,040,000 ; mean = 

 1,020,000 per c.c., indicating some redaction, but still enormously 

 high numbers present. 



Two plates from the exposed flask F 2 , after the five and a half 

 hours' insolation, gave 595,000 and 1,295,000 ; total, 1,890,000 ; mean, 

 945,000. 



of Bacill as r in Sterile Water. 



per square as near as could be counted. 



