HOW SAP RISES

Nelson Evening Mail, Volume LVI, 23 November 1922, Page 2

HOW SAP RISES

' Svir Jagadis Bose, of Calcutta, . is famous fin' Ins investigations into • the physiology of plant life. He is about 1 to publish a not he; work upon that subject, ami has given an indication of its contents in a newspaper contribution, which is already attracting much attention among scientists. It is, ot course, commonly known that, trees or plants obtain their inorganic food materia! from dissolved substances in the soil. They suck up the water by the. root, and the moisture is transpired into the air by the leaves. The quantity of water thus raised is much larger tlnin moslgpeoplc tire aware id. A big tree, for instance., will get rid of a hundred pounds a d<\Y- The energy re* quired for jsydng thus weight of water is very great. How the nioisUu'c is raised upwards has been a secret of nature for all time. Sir Jagadis Bose has now unravelled that mystery. It. has long been disputed whether the sap is lifted by living cells, or by sue-' tional force, developed by the physical evaporation of the leaves. As the result of many experiments in the professor's research institute at Calcutta, ir has now been established that., the rising of the sap is due to the activity of living cells. In the course of those, experiments the use of specially constructed instruments showed 4 that under favourable circumstances, sap will rise at the rate of one bundled feet per hour. Such a velocity of ascent was deemed to preclude the theory of capillary action or atmospheric pressure. By exploring every outside skin to the pith inside, while the plant was still functioning, Professor Bose was able to discover that (lie pumping process was the work of a living organism. Professor Bose devised an electric p'obe, which he attached to a sensitive galvanometer. This instrument gave surprising results. It showed Pvt the cells’ in the active layer of a tree work with a throbbing pulsation, alternately expanding aqd contracting, absorbing water from below and expelling it upwards. The period of a single pulsation • in'the most effective experiments was estimated at Id seconds, These cells are confined to the cortical .sheath, which extends throughout the whole length of every tree. There is, also, a certain limited amount of water storage from what one, may • call reserve purposes, in the wood vessels of the tree. 'This storage is also supplied by the same pulsations. Professor Bose’s experiments establish the fact, of a wonderful similarity in heartbeat records of animals and plants. In the animal, then l is an increasing heart, beat under a temperature ; the pulse beat of a plant, is similarly increased under similar conditions. There is a converse effect Tinder a low temperature. This explains the drooping of leaves under a frost. It is also shown that the plant, like the animal, contracts under a shock, for both plants and animals have a well-devised nervous system. Drugs affect the animal ami plant alike. Professor Bose declares there is no characteristic action on the highest animal that - has not a counterpart in the simpler life of the plant.