IN TOUCH WITH NATURE

Hokitika Guardian, 18 July 1931, Page 7

IN TOUCH WITH NATURE

PLANTS ARE LIKE ANIMALS. (By J. DRUMMOND, F.L.S. F.Z.S.) I ——— Some 20 years ago it was generally believed that the life-movements . of plants were very different from the life-movements of creatures, that is, of all animals, meaning, all animal life, to use the word in the wide 6ense in which it is used by biologists. When Sir J a gad is Chunder Bose, founder and director of the Bose Research Institute, Calcutta, announced that the remarkable movements of the sensitive plant, Mimosa, which inspired Shelley in the realms of poetry, are accompanied by signs that- characterise the contraction of animals’ 'muscles, the announcement was received with incredulity. It was felt that his interpretations of the phenomena he had observed were opposed to the principles behind the actions and functions of plants. His latest work, “The Motor Mechanism of Plants,” a. copy of which has been sent by the publishers, shows beyond doubt that the sensitive plant reacts directly to stimulation in the same way as the muscles of animals react.

Further than this, ordinary, nonsensitive plants respond to stimulation by movement which is not always perceptible, but which can he detected by sensitive apparatus with high magnification. The response is not limited to some plants, but is made by them all. Further still, he has demonstrated that, just as in the body of an animal .there is rhythmic movement of internal organs concerned with the propulsion of food along the alimentary canal, so in the body of a plant there is a similar movement in a tissue that propels the >sap. All experiments that affect the movement of an animal’s heart or stomach, affect in the same way the activity of the tissue that causes in the plant propulsion of the sap. There is a common factor in the mechanism that moves plants and animals. These experiments give the study of the life of the plant a higher significance and importance. Their author ihopes that they will even point the way to a solution of many perplexing problems in the liveis of animals.

The instruments demonstrate that Mimosa is hypersensitive to variations of light. Even a passing cloud induces a marked change. One leaf of a Mimosa plant showed signs of fatigue. Ozone brought about an immediate change. Carbonic acid gas, on the other hand, has an asphyxiated action. Ether' has a dejiressihg effect oh plants. 1 The vapour of chloroform acts as a very strong narcotic. Any excess of its application is fatal. A large dose of chloroform not only produced a total abolition of excitability, but also caused a sudden spasm the spasm of death. Mimosa is not uniformly sensitive. In one case, in the spring, the sensitiveness reached its maximum about mid-day, and remained, constant for several hours. After that there was a continuous deorease, the minimum being reached about 8 a.m. the following day, when the plant was practically insensitive.

The symptoms of death in plants such as drooping, withering, and discoloration do not manifest themselves at the moment of death, but much later. At the moment of death violent excitation is developed in the plant’s tissue. A fairly large number of experiments proved that the rhythmic mechanism in plants and in animals is essentially similar. There are drugs that cause arrest of the heart and drugs that revive its activity. The same drugs applied to the pulsating leaflets of plants .produced parallel effects. The action of extracts of some Indian plants on the pulsation of leaves led to the discovery of their action on the animal heart.

One of the most delicate instruments used in the experiments is a high-mag-nification sphygmograph, which records pulsations of the sap. Instruments of different degrees of sensitiveness were devised. The first gives a magnification of from 1000 to 5000 times; the second carries it to 25,000 times; the third to 10,000,000 times. The third and highest magnification is necessary to obtain a record of the individual pulse-wave in the propulsion of sap. By these experiments it was proved that somewhere in the interior of the plant there is an active tissue the pulsation of which, on the principle of a pump, affects the propulsion of the sap, .in the same way as the pulsation of 'the heart maintains the circulation off the blood in animals. The venom of a cobra permanently stops pulsation, causing the plant’s death. All the results obtained show that the mechanism for the propuls : on of sap in a plant is similar in principle to the mechanism for circulating blood in an animal. The author of this notable book has skilfully arranged his facts and conclus'ons. *He has brought the plant and animal kingdoms closer together, showing that in the field he has investigated, one great principle runs through bo h.