TRANSPIRATION BEHAVIOR OF RAIN-FOREST PLANTS. 



79 



In table 29 and fig. 1 1 are shown the mean daily relative transpiration 

 curves of Pilea nigrescens, Peperomia turfosa, and Diplazium celtidi- 

 folium, as determined respectively from the 84, 82, and 54 readings of 

 tables 23, 24, and 25. There is a general similarity in the three curves, 



I I I I I 



10 11 12 1 r. M. : 



I I 



Fig. 10. — Relative transpiration graphs for successive experi- 

 ments with Diplazium celtidifolium. Each individual 

 plant used is designated by the same letter throughout. 

 (For values see table 18.) 



save for the tardy maximum of Peperomia and its low rate at the 4 p.m. 

 and 5 p. m. readings. The rise of Diplazium at the 8 p. m. and 9 p. m. 

 readings will be commented on later, in connection with its stomatal 

 behavior. It may be observed here that the nocturnal relative rates 

 are in no case as low as the lowest of the diurnal rates. 



Inasmuch as several of the experiments show that there is a" break" 

 in the morning rise of relative transpiration, before the hour at which 

 the maximum evaporation of the day is recorded, an indirect method 

 was employed to determine whether a progressive increase of evapo- 

 ration rate is attended by a definite behavior on the part of the relative 



