﻿BOTAX/CAL GAZETTE 



produced by experiment make the general nature of the phenome- 

 non clearer. As the intensity of the sun in the east increases, the 

 west leaflets of a leaf, oriented north and south, usually exhibit 

 the xerofotic movement before the east leaflets. It was demon- 

 strated experimentally that in this response the paired condition 

 of the leaflets is of less importance than in other movements. 

 Even in the very sensitive Mimosa pudica, one leaflet of a pair is 

 frequently bent more in xerofotic response than the other; while 



Fig. i.—Leucaena glauca against the sky, showing amount of light cut off by 

 leaflets in the horizontal position; compare with fig. 4; !<<>s Hafios, P.I.July 20, 1014- 



in the disturbance of turgidity caused by shock, the pairs act 

 equally and simultaneously. This suggests that xerofotic condi- 

 tions of unequal turgidity are very little, if at all, transmitted. 

 All the leaflets of a compound leaf do not necessarily respond 

 equally. Sometimes there is an obvious reason, for the basal 

 leaflets are shaded. In other cases, only the hypothesis that the 

 the basal leaflets are better and more quickly supplied with water 

 to equalize the turgidity seems to explain the discrepancies in 



Seasonal relations.— This movement is not peculiar to any 

 season, but is present throughout the year. In - the dry season the 

 xerofotic position is regularly assumed a short time after the sun 



