352 



Profs. Percy Frankland and Marshall Ward. 



Tab 



xiv. 



On August 28 another pair of flasks (F 9 and P 10) were exposed 

 as before, 10.30 A.M. till 6.80 P.M., and left out all night ; exposed 

 next day from 10 A.M. to 4 P.M. The sky was cloudy on both days, 

 but there was a good deal of sunshine also, particularly on August 29. 

 We estimated the actual exposure to daylight as 18 hours, and about 

 8 hours' good sun altogether. 



In order to extend our numbers whence we drew the average of 

 bacteria present at the commencement, twelve samples were taken 

 for plates to begin with, and we diluted to 1 in 10 as before. 



After three days' incubation we found four of the plates too far 

 liquefied to count, but the numbers would probably not be incon- 

 sistent with the following : 



The eight plates gave a total of 10,890 colonies, and an average of 

 1361 colonies per c.c. in the water at the commencement of the experi- 

 ment. 



After the exposure to light and darkness from 10.30 A.M. August 

 28 to 4 P.M. August 29, we found about 300 per c.c. in the flask ex- 



