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 XXI

ELECTRIC RESPONSE IN ORDINARY PLANTS UNDER MECHANICAL STIMULATION

Discovery of the similarity of response in inorganic substances and in animal tissues led me to the investigation of responsive phenomena in the intermediate region of life of plants.

The action of stimulus on living substances is usually detected by two different methods. In the case of motile organs, stimulus causes a change of form. Mechanical response may thus be obtained in a contractile tissue such as a muscle. But in others, nerve for example, stimulus causes no visible change; the excitation of the tissue may, however, be detected by characteristic electromotive changes. The advantage of the electric mode of detection of response is its universal applicability. In cases where mechanical response is available, as in the muscle, it is found that records of mechanical and electrical responses are very similar to each other.

The intensity of electrical response in animal tissue is modified by the physiological activity of the tissue. When this activity is in any way depressed, the intensity of electrical response is also correspondingly diminished. When the tissue is killed, the electrical response disappears altogether.

Burdon Sanderson, Munck, and others found electric response to occur only in sensitive plants. I wished to find out whether the responsive electric variation was confined merely to organs of plants which exhibit such remarkable mechanical movements, or whether it was