MARVELS OF GROWTH AS REVEALED BY THE "MAGNETIC CRESCOGRAPH"
[Sir J. C. Bose has recently invented the "Magnetic" crescograph. It is a supersensitive instrument and the very high magnification obtained by it surpasses all existing appliances. By this instrument, phenomena hitherto beyond the reach of investigation can now be studied with great precision. It shows ultra-microscopic changes inducted in a growing organism even by a puff of smoke or a gentle breeze, by a passing cloud or fleeting brightness. This super magnifier was exhibited for the first time by Sir J. C. Bose before an appreciative gathering 10-1-1919. A number of lady students, professors, lawyers, doctors and several eminent personages gathered to hear the great Indian scientist.]
In his Discourse on the above subject on Friday, Sir J. C. Bose illustrated how the limitations imposed on the advance of science by the imperfection of our senses, may stimulate the invention of supersensitive apparatus which reveals to us the existence of phenomena hitherto unknown. Thus the invention of the microscope from a simple lens magnifying 3 or 4 times into progress up to 1500 diameters has given birth to new sciences. But still higher magnification is demanded in unravelling the mystery of movements associated with the simplest type of life as seen in plants. Greatest potentiality in life is often latent; the gigantic banian tree grows out of a thing which is smaller than the mustard seed. Within the seed-coat the dormant life remains in safety, protected from dangers outside. The seeds may thus be subjected without harm to cold so intense as will freeze mercury into solid and air into liquid. Winds and hurricanes scatter the seed of life and the cocoa-nut rides the tumultuous waves till anchored safe in an island yet to be inhabited. In due season there begins a series of most astonishing transformations; the latent life wakens, and the seedling begins to grow. The root turns downwards and the shoot upwards. Underground, the root winds its way round stones and obstacles towards moist places. Above ground the stem bends as if in search of light. Tendrils twine about a support. These visible movements are striking enough, but within the unruffled exterior of the plant body there are others, energetic and incessant, which escape our scrutiny. The bending of a growing organ towards or away from stimulus must be due to unequal growth on two sides of the organ, a retardation of growth on the proximal or acceleration on the distant sides. Various theories have been advanced which have proved inadequate. For the identical stimulus of gravity produces one kind of curvature in the root and the very opposite in the shoot. The possibility of direct experimental investigation has been frustrated by the excessive slow rate of growth rendering accurate measurement impossible.
THE SLOWNESS OF GROWTH
The movement of growth is two thousand times less rapid than the place of the proverbially slow-footed snail. Taking the average annual growth in height of a tree to be 5 ft., it will take a tree a thousand years to cover a distance of a mile. We take a piece of 2 ft. in the course of half a second, during the interval plant grows through a length of 1,100,000 part of an inch or half the length of a wave of light. For investigation on the effect of external conditions on growth we have to measure even a fraction of that excessively small length.
The peasant has eagerly watched the growth of his plants on which his own life and the world's depend and, even realised something of its vicissitudes, so the vegetable physiologist has here one of the many problems of his science. The invention of growth-measuring instruments has thus been one of his main endeavours. He has hitherto succeeded by the use of levers with unequal arms to obtain a magnification of about 20 times, and even then it takes many hours for growth to become perceptible; owing to the practical impossibility of maintaining the external conditions constant for so many hours, the results of measurement of growth become vitiated. It is therefore necessary to produce a magnification so high that growth should become measurable in less than a minute. The first improvement effected by the lecturer, now some fourteen years ago, was his Optical Lever, which at once raised the magnification from 20 to 1000 times, an advance which at the time seemed to many incredible, but it is at length coming into use in advanced laboratories in Europe.
THE RECORDING CRESCOGRAPH
A new apparatus devised by the lecturer, the Recording Crescograph, is described in the Transactions of the Royal Society, and of the Bose Institute. By a compound system of levers the magnification is raised to 10,000 but this is not without great technical difficulties, which cost five years of efforts to overcome. Thus the levers require to be extremely light; this was secured by the use of an alloy of aluminium used in the construction of Zeppelins: this combines lightness with rigidity. Another difficulty almost unsuperable arises from the friction at the bearings of the fulcrum, the best watch jewels made of ruby were employed, but the supply was cut off from Germany by the war. This proved a blessing in disguise, for it forced the lecturer to devise a new principle of suspension using local material. This was found in practice to be far superior to jewel bearings, which became clogged by invisible dust particles present in the air. With this Recording Crescograph many phenomena of extreme interest have been discovered. The plant itself not only recorded its normal rate of growth but the slightest change induced in it by the action of different forces. So delicate was the apparatus that it analysed growth into a series of pulses, a sudden shooting out followed by a partial recoil. It showed how the growth of the plant was retarded by a mere touch, and the time it took the plant to recover from the effect of contact, and all these in course of a few seconds. The effect of different food on growth, the effect of different drugs, or living capacity these and many more became revealed by the automatic record made by the plant. This has opened out fresh and more exact method of medical inquiry, and of practical agriculture.
THE MAGNETIC CRESCOGRAPH
Such unlooked for results called for yet higher magnification, and at first it seemed that further multiplying lever might be added to the previous system. But this failed on account of added mass and friction; and some altogether new solution had therefore to be sought. Material contact having proved unworkable the ideal weightless and frictionless linking was obtained by introducing a new magnetic contrivance, and this with the surprising potency of magnification from 5 to 100 million times. The mind cannot grasp the meaning of this stupendous magnification; how then could we translate it in terms which may be understood? Let us take once more our slow-footed snail, a magnification of ten million times would convert its speed to something for which there is no parallel even in modern gunnery practice. The 15 inch cannon of the "Queen Elizabeth" has a muzzle velocity of 2360 ft. per second or 8-1/2 million feet per hour. But the speed of the snail when magnified ten million times would render it 200 million ft. per hour or 24 times faster than the fastest cannon shot. We may next turn to the cosmic movement for a parallel: A point in equator whirls round at the rate of 1037 miles per hour. But a snail with the magnified speed would beat the earth by going round 40 times during the period the earth makes but one revolution!