TRANSPIRATION BEHAVIOR OF RAIN-FOREST PLANTS. 



93 



and the averages of the variable readings have been used in the tables 

 and curves. As already stated, the measurement of twice the usual 

 number of stomata gave, in no case, a greater difference than 6 per 

 cent between the average diameter of the two groups of 24. 



In table 36 and fig. 15 are given the curves for two experiments with 

 Peperomia lurfosa in which the stomatal readings were taken. The 

 first of these was interrupted at 2 p. m., up to which hour there had 

 been a nearly constant rise of the curves of transpiration and relative 

 transpiration, and a general upward course in the evaporation after 

 8 a. m. The curve of stomatal openness rises in good agreement with 

 the relative transpiration curve, but reaches a maximum at 12 noon 

 and falls at 2 p. m., in spite of the rise in relative transpiration during 

 the same interval. 



E 



4 



1 



E 



If, A. M. 



10 



12 



FIG. 15. Graphs for two experiments with Peperomia turfosa in 

 which determination was made of transpiration (T), evapora- 



. Tp . / T \ 



tion (-. ), relative transpiration (^), and stomatal area (S). 

 4 .bj 



