Life Movements in Plants, Volume I

Name: Life Movements in Plants, Volume I
Author: Bose, Jagadis Chandra

Bose, Jagadis Chandra

Growth (Plants); Plants -- Irritability and movements

+---------------+---------------------------+--------------------+
  |               | Velocity in               |                    |
  | _Biophytum_   |     centrifugal direction | 2.9  mm per second.|
  |               |  "  centripetal    "      |   2  mm  "    "    |
  | _Averrhoa_    |  "  centrifugal    "      | 0.5  mm  "    "    |
  |               |  "  centripetal    "      | 0.26 mm  "    "    |
  +---------------+---------------------------+--------------------+


EFFECT OF TEMPERATURE.

Variation of temperature has a marked effect on the velocity of
transmission of excitation. Lowering of temperature diminishes the
velocity, culminating in an arrest. Rise of temperature, on the
other hand, enhances the velocity. This enhancement is considerable
in specimens in which the normal velocity is low, but in plants in
optimum condition, the velocity being already high, cannot be further
enhanced. The following tabular statement gives results of effects of
temperature on velocity of transmission in _Mimosa_ and _Biophytum_:--

TABLE IV.--EFFECT OF TEMPERATURE ON VELOCITY OF TRANSMISSION.

  +---------------------------+--------------+--------------------+
  |         Specimen.         | Temperature. |     Velocity.      |
  +---------------------------+--------------+--------------------+
  |_Mimosa_ (winter specimen) |     22°C     | 3.6 mm. per second.|
  |                           |     28°C     | 6.3 mm.  "   "     |
  |                           |     31°C     | 9.0 mm.  "   "     |
  |                           |              |                    |
  |_Biophytum_                |     30°C     | 3.7 mm.  "   "     |
  |                           |     35°C     | 7.4 mm.  "   "     |
  |                           |     37°C     | 9.1 mm.  "   "     |
  +---------------------------+--------------+--------------------+


EFFECT OF SEASON.

The velocity of transmission is very much lower in winter than in
summer. In the petiole of _Mimosa_, the velocity in summer is as high
as 30 mm. per second; in winter it is reduced to about 4 mm. The
lowering of velocity in winter is partly due to the prevailing low
temperature and also to the depressed state of physiological activity.


EFFECT OF AGE.

In a _Mimosa_ plant, different leaves will be found of different age.
Of these the youngest will be at the top. Lower down, we obtain a fully
grown young leaf, and near the base, leaves which are very old. The
investigation deals with the effect of age on the conducting power of
the petiole.

Public-domain text, read in full here on John Shaqi.

Life Movements in Plants, Volume I

No reviews yet