LAWS OF STIMULATION 



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different methods employed are the mechanical response of 

 motor organs, the response of growing organs by variation 

 in the rate of growth, and the response by electromotive 

 variation. It has thus been possible to formulate the Laws 

 OF Direct and Indirect Stimulation : 



1. Direct Stimulation : 



The effect of moderate intensity of stimulation acting 

 on organs in favourable tonic condition, is 

 contraction, diminution of turgor, negative 

 mechanical and electric response, negative 

 variation (retardation) of the rate of growth. 



2. Indirect Stimulation : 



{a) The effect of feeble stimulation is expansion, in- 

 crease of turgor, positive mechanical and electric 

 response, positive variation (acceleration) of the 

 rate of growth. 



(b) The effect of prolonged application of stimulus of 

 moderate intensity is a diphasic response, posi- 

 tive mechanical or electric response followed by 

 the negative ; an acceleration followed by a 

 retardation of growth. If the intervening tissue 

 be highly conducting, the transient positive 

 effect becomes masked by the predominant 

 negative. 



These fundamental effects of direct and indirect stimula- 

 tion are instrumental in bringing about various tropic 

 curvatures. The following table gives the responsive effects 

 induced in pulvini and in growing tissues. 



Table XV. — Showing Responsive Effects Common to Pulvini 

 AND Growing Organs under Unilateral Stimulation. 



