244 CHAP. XXII. DIURNAL MOVEMENTS OF PLANTS 



1. The stage of normal anisotropy, when A is the 



upper side and contracted ; 



2 . The transitional, shortly after inversion (A below) ; and 



3. The stage of reversed anisotropy, when the plant is 



geotropically readjusted in the new position (A 

 below and expanded). 



Fig. 141. Effect of inversion of the plant on diurnal movement. 

 a, normal record; b, record 24 hours after inversion, and 

 c, after 48 hours. (Tropaeolum.) 



Experiment 132. — The normal, the transitional and the 

 reversed diurnal records were obtained with an identical 

 horizontal stem of Tropaeolum subjected to stimulus of 

 gravity (fig. 141). In a is seen the normal diurnal curve 

 when the surface A was uppermost ; the specimen was 

 then inverted, and it took nearly two days for the stem to 

 readjust itself to the new state of geotropic equilibrium. 

 The record b was recommenced 24 hours after inversion; 

 the persistence of the previous movement is seen in the 

 reversed curve during the first half of this record ; but in 



