* Golden bell. l. 440. There are muscles placed about the footstalks of the leaves or leaflets of many plants, for the purpose of closing their upper surfaces together, or of bending them down so as to shoot off the showers or dew-drops, as mentioned in the preceeding note. The claws of the petals or of the divisions of the calyx of many flowers are furnished in a similar manner with muscles, which are exerted to open or close the corol and calyx of the flower as in tragopogon, anemone. This action of opening and closing the leaves or flowers does not appear to be produced simply by irritation on the muscles themselves, but by the connection of those muscles with a sensitive sensorium or brain existing in each individual bud or flower. 1st. Because many flowers close from the defect of stimulus, not by the excess of it, as by darkness, which is the absence of the stimulus of light; or by cold, which is the absence of the stimulus of heat. Now the defect of heat, or the absence of food, or of drink, affects our sensations, which had been previously accustomed to a greater quantity of them; but a muscle cannot be said to be stimulated into action by a defect of stimulus. 2. Because the muscles around the footstalks of the subdivisions of the leaves of the sensitive plant are exerted when any injury is offered to the other extremity of the leaf, and some of the stamens of the flowers of the class Syngenesia contract themselves when others are irritated. See note on Chondrilla, Vol. II. of this work.
From this circumstance the contraction of the muscles of vegetables seems to depend on a disagreeable sensation in some distant part, and not on the irritation of the muscles themselves. Thus when a particle of dust stimulates the ball of the eye, the eye-lids are instantly closed, and when too much light pains the retina, the muscles of the iris contract its aperture, and this not by any connection or consent of the nerves of those parts, but as an effort to prevent or to remove a disagreeable sensation, which evinces that vegetables are endued with sensation, or that each bud has a common sensorium, and is furnished with a brain or a central place where its nerves were connected.
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