136 BOTANICAL GAZETTE [AUGUST 
the records of two atmometers. The instruments were prepared 
on a scale as given by LIvincsTon (14). The integration of humidity, 
temperature, and air-current data given in a weekly rate varied be- 
tween 200 and 270°. 
Fic. 2.—Wheat plants from various cultures of bog water and bog soil. Numbers 
as in the text, p. 133. Six plants from each solution. : 
As an aid for comparing the rate of growth of similar plants ™ 
different media various criteria were used. The main emphas!s, 
however, is placed upon the total transpiration for a definite period 
of growth, since the difference between the amounts of water lost me 
been shown to be equivalent to the difference between the physiolog! 
