WATER CONTENT OF PLANT PARTS. 



47 



Since the manner of shading used in the transpiration method described 

 above requires attention at least as often as every 10 minutes, it was not 

 practicable to obtain both transpiration and water content readings on the 

 same day, and in order to obtain the two sets of readings in comparable 

 form the water content experiment was preceded and followed by transpi- 

 ration readings, transpiration of branch / (see p. 31) being taken on Sep- 

 tember 14, water content on September 15, and transpiration of branch g 

 on September 16. No samples were taken from the limb from which came 

 the branches used for transpiration. 



In order to obtain an approximation of the water content at the time 

 corresponding to the transpiration readings, which it will be remembered 

 were plotted to the middle of the time period, lines were dropped from the 

 transpiration readings until they intersected the curves of water content 



TABLE 21. Water content of leaves and their twigs. Experiment XIX. 



Twigs 



Water content 



9 P. M. 



FIG. 23. Graph for moisture content of twigs and their leaves for September 15, 1912, 

 plotted with relative transpiration for September 14 and 16. Exp. XIX. 



