ROBINIA. 123 



movements of the leaves for which the Locust is so remark- 

 able ? When, in securing your specimen, you grasped the 

 branchlet, the leaves felt and, as it were, resented the 

 violence. Did you not notice how they fell forward 

 toward the branchlet, while every leaflet be.nt forward 

 and upward until each met its fellow as if in sympathetic 

 embrace ? 



Similar movements occur at evening with the departure 

 of the sunlight. Then not a few leaves only, but the count- 

 less host on every branch bend, bow, and fold their leaflets 

 face to face, and so sleep through the hours of darkness. 

 When the dawn wakens the Robin to his song, it also wakes 

 the Robinia, and her leaves with the advancing light slowly 

 unfold to the sweet influences of the vital air.* 



The True Sensitive Plant (Mimosa pudica) 

 is native in tropical America from the Isthmus 

 to Brazil. Its flowers are collected in roundish 

 heads, its fruits are legumes of a peculiar pattern 

 called laments, having joints between the seeds 

 (5). The leaves are twice compounded (digi- 

 tate-pinnate). When expanded, they are broad 

 and showy, covering the plant with verdure. But 

 at a touch of the finger, or the wing of a bee, they 

 fold up and contract, one after another, so as 

 almost to vanish from sight.f This results from a 

 series of motions as follows : 1st, the numerous 5 ' a lom ent. 

 leaflets move upward and forward, twins meeting and 

 together covering the pair next before them ; 2d, the four 

 divisions thus folded move toward one another as a fan 



* The leaves of our Wild Cassias, which open their yellow flowers in August, are 

 also very sensitive, closing their numerous leaflets when touched. 



t At Aspinwall, the traveler, first stepping from the car into a dense green patch 

 of Mimosa, is confounded at seeing the whole patch disappear, leaving the ground 

 almost bare, and again after a few minutes looking as verdant as ever ! 



