218 



PLANT RESPONSE 



sphere is now in stable equilibrium, under the directive action 

 of the earth, and the mutual action of the needles ; hence the 

 north pole of each needle, represented by the arrow-head, 

 points to the north, which is, say, to the left. The disturb- 

 ance of any individual sphere, say E, brings about the 

 disturbance of its neighbour, and, owing to the mutual 

 magnetic action between contiguous north and south poles, a 

 derangement initiated in this way is transmitted onwards. 

 Such a disturbance may be initiated by means, for instance, of 



Fig. 95. Molecular Model Exhibiting (a) Excitability at the Receptive 

 Area ; (b) Conductivity of Intervening Region ; and {c) Mechanical 

 Response of Terminal Responder 



Disturbance is initiated at the sphere connected with E, by the magnetic 

 action of the electro-magnet seen to the right. This disturbance is con- 

 ducted by the intervening spheres and reaches the terminal responder, r. 

 Molecular viscosity is increased by immersion of attached dampers in 

 viscous fluid. 



a small electro-magnet, placed at right angles to the molecular 

 magnet in E. This electro-magnet is magnetised for a short 

 time by the tapping of a key, which closes an electric current, 

 causing a rotation of the sphere E. The intensity of this 

 disturbing force, the stimulus, may be increased at will, by 

 appropriate exaltation of the strength of the magnetising 

 current (fig. 95). 



In such a row of molecules, then, that to the extreme 

 right, E, is the point at which we shall initiate molecular 

 disturbance. That is to say, it corresponds to the receptive 



