494 



LIFE MOVEMENT?; IN PLANTS 



Exijeriment 189. — The investigation was carried out 

 with the stem of Bryoph/fl/um, and the flower stalk of 

 Njpuplicea. The probe %vas made to enter the organ througli 

 ()-4 mm. and the geo-electric effect found, on rotation of the 

 flower stalk of Nymphvea from the vertical to the horizontal, 

 was a deflection of +G divisions of the galvanometer. Tlie 

 change, induced at the loiver side hu geotrojjic stimulus is thus 

 galvanoraetric positivity, indicative of enhancement of turgor, 

 aiul of expansion. Intrusion of the probe thfough (V6 mm. 

 gave rise to an increased positive geo-electric response. 

 Tliat the sign of electric response depended on the relation 

 of the side of the organ to the vertical lines of gravity 

 was demonstrated by alternate rotation of the plant through 

 + 90° and -90°, the probe remaining at a definite position. 

 Rotation through +90 brought A above, and rotation 

 through - 90 ' brought A below. When the probe was in 

 the up position the geo-electric response was negative, but 

 when rotation through - 90 ' brought it hdoiv, the response 

 became positive. Thus with an identical contact in the 

 plant, the electric response underwent reversal from 

 negative to positive. This will be understood from the 

 following table. 



It will thus be seeu that physiological change induced 

 at any point is modified by its relation to vertical lijies of 

 gravity. When the point is above, the induced change 

 is negative, when below, the induced change is positive. 



I shall next describe the variation of effect at 

 ent layers of the under side of the organ. 



diff'er- 



