1914] 



OTIS— TRANSPIRATION OF WATER PLANTS 



485 



leaf and water surfaces. It is said (8) that the purple coloring 

 matter of the lower side of the lily leaves absorbs the sun's rays and 

 in this way tends to increase the internal temperature of the leaves 



CHART 



30 31 



August 



5X8 9 10 11 12 



September 



16 X19 20 X 23 34 



1911. 



and hence the transpiration. Experimental evidence seems to be 

 lacking on this point, and it is the belief of the writer that, assuming 

 any slight changes in temperature to be probable, they would be 



