1903 Nervous Mechanisms of Plants 321 



to plant life ; whenever there was protoplasm capable of 

 movement, it was always labelled as " animal " life ; but 

 scientists have discovered, and assure us, that protoplasm, 

 whether it is found in animal or vegetable bodies, is capable 

 of movement under certain conditions. There is a variety of 

 movements in plants due to numerous causes. There is the 

 spontaneous flow of circulation of protoplasm in living cells, 

 and the spontaneous movements of plants during natural 

 growth. Other movements than these require a stimulus 

 from outside to set the machinery in motion. The elements 

 which stimulate plants are heat, cold, light, and moisture, 

 whilst contact with foreign bodies and chemical stimuli are 

 responsible for the actions in some cases. The fact that 

 the living protoplasm of plant cells communicates through 

 the walls of those cells from one to another is sufficient to 

 lead us to the conclusion that this must be the means by 

 which telegraphic messages are conveyed from the outer 

 cells, which directly receive the stimulus, to the inner ones, 

 so that the whole system of cells shall work in concert. 



This fact makes the theory of nerves in plants more 

 clearly acceptable, if with reservations. If there are nerves 

 in plants they are only rudimentary ones — nerves which in 

 animals are much more highly developed and localised 

 according to their powers. If, as has been suggested, the 

 highly organised power of sight in animals is echoed, how- 

 ever faintly, in the actions of plants under the influence of 

 light, may not taste and smell have something to do with 

 the phenomena of chemiotaxis as well as chemical affinity ? 

 Hearing alone seems to have not the slightest trace of 

 existence in the marvellous catalogue of plant senses. 

 Touch, of course, is even more distinctly apparent than 

 any of the foregoing. Here, indeed, we have wonders 

 which are quite deep enough to puzzle the wisest, so that 

 we need not concoct absurdities which may not be supported 

 for a moment, finding that the borderland between the 

 powers of the animal and vegetable creations is much 

 narrower than we had dreamed. As in animal life certain 

 senses or functions are suspended when the creature is out 

 of health, so also plants must have the necessary " tone " if 

 the " nerves " are to act properly, or sufficiently to exhibit 



