CurTIS: SOME OBSERVATIONS ON TRANSPIRATION 373 
This supposition became more manifest when the stems and 
petioles of several plants of Fzcus elastica were sealed and the rate 
of transpiration in the dark was measured for three hours after 
which the stomatal surfaces were sealed and the rate of cuticular 
transpiration was determined for four hours. This amounted to 
from 3.6 to 10 per cent. of the former volume. 
The physiological character of transpiration is also indicated 
by the periodicity of the opening and closing of the stomata. 
_ They are more responsive to the stimulus of light in the morning 
than in the afternoon and the more considerable physiological 
activity in the morning is manifest in the more pronounced after- 
effect following the illumination in the forenoon. 
