252 Rev. P. Keith on the Stiscept'ibilities of Living Structures. 



stimuli. — 1st. If a leaflet of the sensitive plant Mimosa pudica 

 is but touched, however slightly, by any extraneous body, it 

 immediately shrinks into itself, and communicates the impulse, 

 if strong, perhaps to the whole wing, each pair of leaflets col- 

 lapsing in succession till they meet on the upper side of the 

 leaf-stalk, and the leaf itself sinking downwards, as if by a 

 joint, at its point of union with the stem. If a leaf of Z)/o?z<^a 

 muscipula is touched with any sharp-pointed instrument, or if 

 an insect but alights upon it, the segments immediately col- 

 lapse, and adhere together so closely that the insect is gene- 

 rally squeezed to death in their grasp, or at the least detained 

 a prisoner. — The leaves of several species of Drosera have a 

 similar susceptibility, and act also as fly-traps. — 2ndly. If the 

 inner side of the filament of Berberis communis^ at or near the 

 base, is accidentally or intentionally touched with the point 

 of a quill or bristle, or other suitable instrument, it imme- 

 diately bends itself inwards, and descends till its anther strikes 

 against the stigma*. — Srdly. \i i\\e stigma oi the. naturally re- 

 flected pistil of Styliditivi J'ruticosuvi is touched with the point 

 of the finger, the style is immediately put into motion, and 

 flies over to the contrary side of the flower, till it becomes re- 

 flected on that side as much as it was on the other side. 



Still we have no certain or decided proof that plants are 

 endowed with the attribute of sensation. The irritability which 

 they exhibit upon the application of extraneous or artificial 

 stiimdi does not prove the fact. Sir J. E. Smith found that 

 the stamens of the flower of the Barberry retained their con- 

 tractile power even when the petal with its annexed filament 

 had fallen to the ground, and could no longer be said to be 

 in a living statef . But a faculty which plants may retain even 

 when dead, is surely no proof of their having been endowed 

 with sensation when alive. Besides, they present no apparatus 

 whatever of feeling, or of perception, — nothing that is ana- 

 logous to the brain, nothing that is analogous to the nerves, 

 of animals. — But does not the Mimosa, it may be said, even 

 shrink from the touch? — There is a great difference between 

 a mere shrinking from the touch, and a shrinking from danger 

 apprehended, as in the case of animals. — The harlequin that 

 is made of goldbeater's skin shrinks from the touch or heat 

 of the hand, and tumbles about as if it were actually alive ; 

 but no one, in spite of all its apparent freaks, supposes that it 

 feels. — Might not the phasnomenon of the irritability of plants 

 be accounted for from the influence of the electric or gal- 

 vanic fluid, without having recourse to the faculty of sensa- 



• Smith's Introd. p. 325. Edit. prim. f Ibid. p. 22G. 



tion ? 



