Life Movements in Plants, Volume IIBose, Jagadis Chandra
Science
Life Movements in Plants, Volume II
Bose, Jagadis Chandra
Growth (Plants); Plants -- Irritability and movements
The geo-electric reactions that have been described were obtained under
unfavourable conditions of climate and of temperature. But under better
conditions the reaction becomes very greatly enhanced, as would appear
from the following account of results which I obtained on two separate
occasions in the beginning of August. The season had not become quite as
unfavourable as towards the end of the month, but the prevailing sultry
weather had caused great depression of the geo-electric excitability.
On the first occasion referred to, thunderstorm had broken out at night,
and it was refreshingly cool in the morning. It was with the utmost
surprise that I noted the astonishing violence of the geo-electric
response which the plants gave that morning; the maximum response
hitherto obtained was about 100 divisions of the galvanometer scale; but
on the present occasion the displacement of the plant, from vertical to
horizontal position, induced responsive deflection so great that the
galvanometer spot of light flew off the scale of 3,000 divisions. I was
at first incredulous of the results and wasted the valuable occasion in
trying to discover some hidden source of error. Subsequent tests showed
that my misgivings were groundless, and that the extraordinary large
deflection was really due to geo-electric reaction. On the second
favourable occasion, which lasted for three hours (during the cool hours
of the morning), I was able to secure a number of important
observations. Thus displacement of the flower stalk of _Nymphæa_ through
+90° was immediately followed by geo-electric response, the deflection
being about 3,000 divisions of the scale. The latent period hardly
exceeded a second; the return of the plant to the vertical position was
quickly followed by electric recovery which was complete. The above
results were obtained with the same specimen time after time without a
single failure. The successive responses showed no sign of fatigue.
Another remarkable effect was noticed during gradual increase of the
angle of inclination. Nothing happened till a critical angle was
reached, which was roughly estimated to be about 33°; when this critical
angle was exceeded by a single degree, there was a sudden precipitation
of geo-electric response. The experiments were repeated time after time
with the identical result. It appeared as if some frictional resistance
obstructed the displacement of the geotropic particles accumulated at
the basal end of the cell, and it was not till the organ had been
tilted beyond 33° that this resistance to sliding was overcome.
SUMMARY.
The electric distribution induced in an organ under the stimulus of
gravity may be mapped out by means of an exploring Electric Probe.
The induced galvanometric negativity of the upper side of an organ
(indicative of excitation) undergoes variation in different layers of
the organ. The excitatory reaction attains a maximum value at a definite
layer, beyond which there is a decline.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account