Outlines of human physiology . ly delights, the vast interval that exists bertween minerals and plants is rendered less apparent;and the yet wider break between beings that have lifealone, and those which both live and feel, is so artifi-cially concealed, that we can scarcely determine atwhat point in creation it occurs. I recently examined, with Mr. Gilbert Burnett, themotion of the leaves of the mimosa pudica. Many of 12 Of the Motion of the Sensitive Plant. the facts which we noticed had been abeady describedby Dr. Dutrochet, and were discovered many yearsearlier by Mr. Lindsay: an account
Outlines of human physiology . ly delights, the vast interval that exists bertween minerals and plants is rendered less apparent;and the yet wider break between beings that have lifealone, and those which both live and feel, is so artifi-cially concealed, that we can scarcely determine atwhat point in creation it occurs. I recently examined, with Mr. Gilbert Burnett, themotion of the leaves of the mimosa pudica. Many of 12 Of the Motion of the Sensitive Plant. the facts which we noticed had been abeady describedby Dr. Dutrochet, and were discovered many yearsearlier by Mr. Lindsay: an account of some of themwill serve to illustrate the preceding remarks. The sensible motions of the mimosa pudica are con-fined to the joints, 1, of the leaf-stalk or petiole, withthe stem or branch; 2, of the sub-petiole with theleaf-stalk; 3, of the sub-leaflets with the the day-time the leaf-stalk is raised, the leaf-lets diverge, and the sub-leaflets are expanded inthe manner shown in the adjoined sketch. Fig. In a plant sickly from exposure to cold, this posi-tion of the leaves is permanent; and no sensible mo-tion follows any kind of excitement, that may be em-ployed. When the plant is healthy, on the contrary, it Of the Motion of the Sensitive Plant. 13 is difficult to approach it without causing several ofthe leaves to fall. If the plant be shaken, all drop atonce at their joints; at the same time the leaflets ap-proach each other, and the sub-leaflets become folded in pairs, ^i-. the manner represented inKg. 2. \t| If the stimulus applied bepartial; if, for instance, it con-sist in cutting a single sub-leaflet, that sub-leaflet instantlyrises with its fellow^; then thenext pair, and so on in succes-sion, till all upon the same leaf-let are folded : the petiole thendrops at its joint; and after-wards, all its remaining leafletsclose. If a sub-leaflet have beenburnt, the excitement extendsfrom one leaf to those adjoining;or if applied to the stem, o
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