TRANSPIRATION BEHAVIOR OF RAIN-FOREST PLANTS. 



81 



followed by an abrupt fall, but the general trend of the smoothed curve 

 is downward; Diplazium exhibits irregular behavior, but its smoothed 

 curve also shows a slight tendency to drop. The number of readings 

 on which the placing of the points in these curves is based may be seen 

 in table 30 to be small in many cases. A very much larger number of 

 readings of relative transpiration, under varying conditions of evapo- 

 ration, would make possible the construction of curves much more 

 nearly representative of the actual influence exerted by a rising evapo- 

 ration rate upon the physiological controls of the leaf and plant. The 



.160 



0.50 



-I I 1 I 1 I I I I I 1 1 I I I ! — ! — I — ! 1 1 1 ! 1 1— 



150 



.100 



0.60 



.200 D.c. 



.150 



/N / 



.100 



0.50 



' ' 1 I I 



I I I I 1 



1 2 3 ■) 5 6 7 8 9 10 11 12 13 14 15 16 n 18 19 



I I I I 1 I 



20 21 22 23 24 25 | 



Fig. 12. — Graphs to show effect exerted upon relative transpira- 

 tion rate by progressive increase of evaporation rate. Data 

 secured for Pilea, Peperomia turfosa, and Diplasium (see 

 tables 16, 17, and 18). Dotted lines are smoothed values. 



