After this day's exposure, which lasted six hours, about half of 

 which was more or less cloudy at intervals and the rest bright sun- 

 shine, the plates made again showed great differences, clearly pointing 

 to the inhibitory action of the sunlight, for the sample of exposed 

 water gave 1584 as against 29,760 per c.c. in the unexposed flask. 



In other words, although flask F 5 had stood fourteen hours in the 

 dark at a temperature not too low for increase, its exposure of about 

 12^ hours to the light had resulted in the reduction of its bacteria to 

 a number below that it started with ; the unexposed flask meanwhile 

 had its bacteria multiplying normally at the rapid rates usual for 

 these waters. Had the sunshine been more intense during this second 

 day, it is by no means improbable that the water could have been 

 completely sterilised by exposure. 



The results discussed above are put into a tabular form in the 

 following Table K : 



2 B 2 



