The motor mechanism of plants / by Sir Jagadis Chunder Bose.

  • Jagadish Chandra Bose
Date:
1928
Catalogue details

Licence: In copyright

Credit: The motor mechanism of plants / by Sir Jagadis Chunder Bose. Source: Wellcome Collection.

    35/469 (page 2)
    It appears from what has just been said that any move- ment of the protoplasm is the result of a previous stimulation, that is, of a disturbance of its equilibrium by some external agent, which is the ‘ stimulus,’ such as a touch, an electric • shock, a sudden variation of temperature or of light. Inas- much as it responds to the action of a stimulus, the proto- plasm is described as being ‘ irritable,' or ‘ excitable,’ or sometimes ‘ sensitive.’ In the simple unicellular organism the whole of the protoplasm is equally contractile and irritable. In the course of evolution, as more and more complex organisms were developed, attaining various degrees of physiological differentiation, the contractile and the irritable functions have come to be more or less concentrated in certain parts of the body and in certain specialised tissues : contractility in the motor organs, and in the contractile tissue termed ‘ muscle ’ in the animal; irritability in the sensory organs receiving and those conducting excitation, and in the tissue termed ‘ nerve.’ But this segregation of function is not absolute. It is most complete in the case of nerve which responds to stimulation without any contraction or other visible indication of its activity : muscle, on the other hand, is both irritable and contractile. In virtue of this combination of properties, conveniently termed ‘ moto- excitability,’ the excitability of muscle is mechanically manifested by its contractile response to stimulation. The excitability of nerve, apart from muscle, can only be detected by the electric variation which it, in common with all the living tissues of the body, undergoes when stimulated, a method which involves the use of the galvanometer. The differentiation of the tissues has never reached in the plant series anything like the same degree as in the animal series ; this is especially true of the motile or con- tractile tissue, as well of the associated nervous tissue. Hence it is only in a general sense that it is possible to apply the term ‘ muscle ’ and ‘ nerve ’ to the contractile and the excitatory tissues of plants. It is not surprising that