﻿GA TES— XEROFOTIC ' MO \ EM EX TS 



of the cells of the lower side causes a movement in the direction 

 from which the desiccating energy comes. The xerofotic position 

 decreases the amount of direct radiant energy received per unit 

 area of leaf, reducing the harmful action of intense sunlight upon 

 the chlorophyll as well as checking transpiration. 



2. Two classes of xerofotic response were noted. In the local- 

 ized type the differential turgidity acts in a limited region, such 

 as in the pulvini of leguminous leaflets. In the generalized type 

 the difference in turgidity is between the upper and lower part of 

 the blade. The localized response was characteristic of all observed 

 species of Leguminosae, but is not limited to that family. The 

 generalized type was noted particularly in the monocotyledonous 

 families Poaceae, Araceae, Marantaceae, and Zingiberaceae. 



3. In nature the response was brought about by direct stimu- 

 lation from the sun. It was artificially simulated by the action of 

 the chemical desiccating agents, absolute alcohol and xylol, on 

 Gliricidia sepium and Ipomoea Pes-caprae. 



4. The amount of movement varied between 45 0 and 70 0 above 

 the horizontal. Movement took place under suitable conditions 

 at any season. The amount of response, even in leaflets of a pair, 

 varied under different conditions of exposure. 



■ Carthage College 



