﻿GATES— XEROFOTIC MOVEMENTS 



was sufficient to bring about the change, but usually it took about 

 20 minutes. Upon taking away the screen the xerofotic position 

 was gradually resumed. When the sun was very hot a little upward 

 curling of the outer end of the leaflet was noticed before the com- 

 plete assumption of the xerofotic position. 



While the screen experiments clearly indicated that drying 

 effects dependent upon exposure to sunlight were fundamental, 

 other experiments sought to produce drying effects independently 



of the sunlight. Two of the common laboratory drying agents, 

 absolute alcohol and xylol, were employed. Several legumes were 

 experimented with, but in the majority of cases, the delicateness 

 of the rachis and the small size of the pulvinus made the experiments 

 a failure. At length, however, a suitable plant was found in 

 Gliricidia septum, in which the leaflets, rachis, and pulvini are large 

 and coarse (fig. 5). In successive experiments, both absolute 

 alcohol and xylol were carefully applied to the upper side of the 

 pulvinus with a small pointed brush. As the drying agent with- 

 drew water locally from the upper cells of the pulvinus, the xerofotic 

 position of the leaflet was gradually assumed. The experiments 



