LOCALISATION OF GEO-PBRCEPTIVE LAYER AOl 



till the orgnii had heen tilted ^beyond ijip that this resis^ 

 taiice, to alidiuff was overcome. 



SUMMARY. 



The electric distrihutioti induced in an organ under 

 tlie stimulus of gravity may be mapped out by means of 

 an exploring Electric Probe. 



The induced galvanometric negativity of the upper side 

 (if an organ (indicative of excitation) undergoes varia- 

 tion in different layers of the organ. The excitatory 

 reaction attains a maximum value at a definite layer, 

 bej'ond which there is a decline. 



The geo-perceptive layer is experimentally localised by 

 measuring the depth of intrusion of the probe for 

 maximum deflection of galvanometric negativity. 



The geo-perceptive layer thus determined is found to 

 be the starch sheath which contains a number of 

 large-sized starch grains. 



The power of geo-perception ^undergoes seasonal varia- 

 tion. It is also lowered by high temperature. 



The geo-electric response undergoes decline with grow- 

 ing sub-tonicity of the specimen ; such specimens exhibit 

 abnormal positive electric response under the stimulus of 

 prick and feeble curvature under geotropic stimulus. The 

 large-sized starch-grains, normally observed in the endo- 

 dermis, are found to disappear in specimens which have 

 become geo-electrically insensitive. 



The electric response of the lower side of the organ 



t(» giavitational stimulus is <d" opposite sign to that of 



the upper side. The electric distribution on the lower 



side exhibits variations in different layers, the maximum 



