Tomato plants have a way of protecting themselves from caterpillars. When any leaf on a tomato plant is bitten by a caterpillar, all the leaves in the plant begin producing special proteins that interfere with the caterpillar’s digestion. Soon, the caterpillar will be disgusted with the taste and will leave the plant alone.
Since plants do not have central nervous systems as do animals, it requires explanation how the wounded leaf notifies other leaves to be on guard for danger. Most scientists believe the messenger to be a chemical circulating in the plant’s fluids. An astonishing discovery by David Wildon, a British biologist, has posed a serious challenge to that belief. In an experiment, Wildon placed electrodes on the surface of a tomato plant and then set caterpillars on a leaf. When the leaf was injured, it discharged a tiny electric current all over the plant’s surface. Every leaf in the plant soon started producing defensive proteins.
Wildon is currently conducting further experiments on the tomato plant and other plants. Having proved the existence of electricity on the surface of the tomato plant, he is now placing electrodes inside the plant tissues to measure possible electric currents there. Many plants flower in the spring, when their leaves sense the exact length of daytime indicating the arrival of spring. How do the leaves transmit that message to the growth pints where buds appear? Wildon suspects it has to do with electricity again, and he is trying to find out.
【題組】This passage is probably an excerpt from
(A) a lecture on rare plants (B) a journal of electrical engineering
(C) a magazine on gardening (D) a popular science magazine
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