1914] 



OTIS— TRANSPIRATION OF WATER PLANTS 



483 



free water surface. Just what is the cause of these variations is not 

 clear, since a survey of the weather conditions for these days gives 



CHART 



14 15 16 17 X 19 

 i U G S T 



20 21 22 X 24 

 19 10. 



no indication of the controlling factors. The fact, however, that 

 the majority of the day rates is greater than that from free water, 

 while all of the nkht rates are less, leads to the supposition that 



