Transverse transmission of effect of stimulus 287 



2. {a) indirect application of unilateral stimu- 

 lus of feeble intensity induces a negative 

 curvature. 

 (h) in a conducting tissue the excitatory 



effect being TRANSMITTED UNDER STRONG AND 

 LONG CONTINUED STIMULATION, INDUCES A 

 POSITIVE CURVATURE, 



IL will thus be seen that the tropic effect is modified by : 



(1) the point of application of stimulus, 



(2) the intensity and duration of stimulus, 



(;>) the conducting power of tissue in the transverse 

 direction, 



(4) the relative excitabilities of the proximal and 

 distal sides of the organ. 



In the following series of Papers the tropic effects of 

 various forms of stimuli will be studied in detail. 



SUMMARY, 



In a semi-conducting !issue Direct stimulation induces 

 a diminution ot turgor and contraction, Indirect stimula- 

 tion inducing the opposite effect of increase of turgor and 

 expansion. 



Unilateral stimulation thus induces a positive curvature 

 by the joint effects of contraction at the proximal, and 

 expansion at the distal side. 



Under strong and long continued unilateral stimula- 

 tion, the excitation at the proximal side is transmitted to 

 the distal side. Transverse conduction thus neutralises or 

 reverses the normal positive curvature. 



