FOLIAGE LEAVES: THE LIGHT-RELATION. 



11 



Fig. 4. Two sensitive plants, showing the motile leaves. The plant to the left has its 

 leaves and numerous leaflets expanded ; the one to the right shows the leaflets 

 folded together and the leaves drooping.— After Kerneb. 



the morning and evening (see Fig. 170). As a result, the 

 plane of the leaf lies in a general north and south direc- 

 tion. It is a significant fact that when the plant grows in 

 shaded places the leaves do not assume any such position. 

 It seems evident, therefore, that the position has something 

 to do with avoiding the danger of too intense light. It 



