TRANSPIRATION BEHAVIOR OF RAIN-FOREST PLANTS. 103 



rates of relative transpiration, however, are not sharply reduced; in 

 fact they are either of the same order of magnitude as in other experi- 

 ments already commented on, or are even greater than in them (com- 

 pare tables 41, 42, and 43, showing rates at high humidities, with tables 

 23, 24, and 25). This is equivalent to saying that the degree to which 

 the conditions of high humidity cut down water loss from the plant is 

 equalled or exceeded by the rate at which they reduce the water loss 

 of the atmometer. I have already called attention to the correcting 



Table 42. Transpiration of Pilea and Peperomia at high humidities. 

 Series run in moist chamber. 



Table 43. Transpiration of five species nl lii<jh humidities. 

 S< lies run in moist chamber. 



Date. 



Oct. 



11 



Hour. 



9 h 30 a.m. 



11 30 a.m. 



l :;n p.m. 



:>, 30 p.m. 



Aver- 

 age 

 tem- 

 per- 

 ature. 



Aver- 

 age 

 hum- 

 idity. 



72.9 93.9+ 

 79.8 98.0 



::, i '.2.4 



Evapo- 

 ration. 



Pilea Peperomia 



hiurescens. turfosa 



.Mi,?, 

 2.55 

 6.30 



0.46 



58 



.01 



T 

 E 



T 

 E 



0.36 

 1.228 .7(ni _'77 

 .097 .35 .056 



Pepen imia Oiplazium 



basell SB- 

 folia. 



ii 20 

 .37 

 . 29 



T 

 E 



1 l' 

 04< 



celtidi- 



folium. 



Ajsplenium 

 alatum. 



T 

 E 



,. T 



1. 



.51 0.74... 



7_'o 2851. OIK) 396 

 ..-.'.i .093 To . 1 1 * 



factor which must be introduced in comparing atmometric readings 

 taken in climates of distinctly unlike conditionsof at mospheric humidity. 

 The differences in the character of the water films presented by the 

 atmometer under arid and under humid conditions would not be mani- 

 fested between atmospheric conditions as similar as those in my moist 

 chamber and those normally prevailing in the physiological laboratory 

 at Cinchona, or would, at least, be so -mall as to be negligible. 



