Transactions of the Bose Research Institute, Calcutta Vol ii, Life Movements in Plants

Abstract

IN this the second volume of the Transactions of the Bose Institute, Sir Jagadis Bose continues to pour out his almost overwhelming wealth of observations. The first chapter of the volume deals with a piece of apparatus to be used with the “high magnification crescograph” which magnifies the rate of growth up to ten million times. As, even with much lower magnifications, the spot of light or point of the lever would soon move off the scale or recording surface, the author has devised a method of balance different from the optical method originally used. In this new method the plant-holder is connected with a series of gear-wheels driven by a falling weight and controlled by a fan governor. By this means the plant-holder can be made to fall at various rates, and thus the growth of the plant is compensated, and we have what is termed the “balanced crescograph.” When the rate of growth is exactly balanced the record will show a horizontal line, and any increase or decrease in the rate will be indicated by a rise or fall in the curve. By this means it is claimed that a change in the rate of growth of only i part in 27,000 can be detected. The method is one of great delicacy, it is clear, but, in view of the fact that the control of the speed of movement is in part frictional resistance, and also of the effect of grit and of inequality in the cutting of the gear-wheels, one would have liked to see the inclusion of a record which would demonstrate that a speed of 0.5 M per sec. was kept constant to 1 part in 25,000 for many hours.

Transactions of the Bose Research Institute, Calcutta. Vol. ii., Life Movements in Plants.

By Sir Jagadis Chunder Bose. Pp. v + xiv + 253–597. (Calcutta: The Bose Research Institute, 1919.) Price 10s. 6d.