By his new and newer methods of investigation, Dr. Bose got a deep and
deeper perception of that underlying unity, for the demonstration of
which he had been labouring since 1901. But the dream of his life was
not yet realised. No direct method of obtaining response record was yet
obtained. Hitherto the response recorder employed was a modification of
the optical lever, automatic records being secured by the very
inconvenient and tedious process of photography (which again introduced
complications by subjecting a plant to darkness and thereby modifying
its normal excitability); and the plant was not automatically excited by
stimulus, besides the results obtained were liable to be influenced by
personal factor. So Dr. Bose set about the invention of an apparatus,
which should discard the use of photography and in which the plant
(attached to the recording apparatus) should be automatically excited by
stimulus absolutely constant, should make its own responsive record,
going through its own period of recovery, and embarking on the same
cycle over again without assistance at any point on the part of the
observer. Great difficulties were encountered in realising these ideal
requirements. They appeared, at first, to be insurmountable. But, with
continuous toil and persistence, Dr. Bose succeeded in designing a long
battery of supersensitive instruments and apparatus, which made the
seeming impossible possible. His ingenious "Resonant and Oscillating
Recorders" gave a simple and direct method of obtaining the record. The
plant, being automatically excited by stimulus, made its own responsive
record. The closed doors, at last, opened. The secret of plant life
stood revealed by the autographs of the plant itself. The great
_sadhana_ of his life now received its fulfilment. "It has been
beautifully said--and it is a law of the moral world as unchangeable as
physical laws--'Ask, and it shall be given you; seek, and ye shall find;
knock, and it shall be opened unto you; for every one that asketh
receiveth; and he that seeketh findeth and to him that knocketh it shall
be opened."[24]