552 ORGANOLOGY. 



periments which were instituted, and which, according to my view, were 

 very imperfect. The conclusions which Meyen comes to from experi- 

 ments of his own and of others, are for the most part unfounded, and are 

 most intimately connected with his prejudice of an analogy between 

 plants and animals. He evidently very frequently obtains the results 

 which he previously wished to arrive at. 



b. Not periodical. 



Perfectly similar movements to those which occur gradually on 

 the change of day and night are exhibited by the leaves of some 

 plants suddenly, or at least with great rapidity, as soon as they are 

 brought under the influence of any external chemical or mechanical 

 agency. The following are pretty nearly all the plants in which 

 these phenomena have been observed : 



Mimosa pudica L., M. sensitiva L., M. casta L., M. viva L., M. 

 asperata L., M. quadrivalvis L., M. pernambucana L., M. pigra 

 L., M. humilis Humb., M. pellita Humb., M. dormiens Humb. 



^EscJiynomene sensitiva L., A. indica L., A. pumila L. 



Smithia sensitiva Ait. 



Desmanthus stolonifcr DeC., D. triqueter DeC., JD. lacustris 

 DeC. 



Oxalis sensitiva L. 



Averrhoa Carambola L., A. Bilimbi L. 



The movement of the leaf of Dionaa muscipula Ell., supported 

 by a winged petiole, appears peculiar. The leaf is furnished with 

 cilia, and on the upper surface covered with stiff hairs. On this 

 surface being touched, for instance, by an insect, the leaf closes 

 together along the central nerves, and the cilia fold within one 

 another, so that the object brought in contact with it is enclosed, 

 and held fast with some force as long as the movement continues. 

 On the latter ceasing, the leaf slowly expands again. In this 

 manner irritable insects are kept captive till they are dead. 



The reproductive organs in some of the Phanerogamia exhibit 

 a sudden movement in consequence of external influences which 

 produces a transference of the pollen from the anther to the stigma. 

 By way of example, we may mention the stamens of Berberis 

 vulgaris, Parietaria judaica, the style of Stylidium adnatum, S. gra- 

 minifolium, Goldfussia anisophylla, &c. The movement takes place 

 also in this case without an external cause, although not so rapidly. 



It cannot be denied that the so-called Sensitive plant (Mimosa pudica\ 

 which folds up its leaves from the shaking of the ground caused by 

 the tramp of a horse, and at every rude touch, presents a most welcome 

 object for poetic treatment ; and the circumstance of this plant not having 

 been known to the old Greeks has certainly made us poorer by one 

 beautiful myth at least. The task of the naturalist, however, is 

 different ; he has other problems to solve, and to him this plant, and 

 its relations in time, must for the present be a land-mark indicating to 

 him the boundary of his knowledge, and a significant warning not to 

 people with the mere creations of his fancy that domain which demands 

 of him earnest and true work. A glance at all that has been done with 



