486 



LIFE MOVEMENTS IN PLANTS 



maximum excitation under the stimulus of gravity, and 

 that this excitation irradiates with diminishing intensity in 

 radial directions inwards and outwards. 



The geo-perceptive layer may thus he experimentally 

 localised by measuring the de^jtJi of intrusion of the probe 

 for maximum deflection of galvanometric negativity. 



Localisation of geo-perce2)tive layer in Nympha3a : 

 Experiment 186. — I employed the same method for the 

 determination of the perceptive layer of a different organ 

 namely, that of the flower stalk of Nymphcea, The electric 

 reaction in Nymphcea^ even under the prevailing unfavour- 

 able condition of the season, was moderately strong, being 

 about three times greater than in Bryophyllum. A dozen 

 observations made with different specimens gave very 

 consistent results of which the following may be taken 

 as typical. The probe was in this case, as in the last, 

 moved by steps of 0*4 mm. at a time. Other examples 

 will be given later where readings were taken for successive 

 steps of 2 mm. 



TABLE XI.I. — SHOWING THE DISTRIBUTION OF INDUCED GEO-ELECTRin 

 EXCITATION IN DIFFERENT LAYERS {NymplKKo). 



It will be seen that as in Bryophyllum, so in Nymphma^ 

 the geo-electric excitation increased at first with increasing 

 depth of the tissue till at a depth of 0-8 mm. of the parti- 

 cular specimen the induced excitation attained a maximum 



