46 RESPONSE IN THE LIVING AND NON-LIVING 
is therefore difficult to fix an absolutely neutral point, 
but a pot may be found which approaches this very 
nearly, and on stimulating the stalk near this, a very 
interesting diphasic variation has been observed. In 
a specimen of cauliflower-stalk, (1) stimulus was applied 
very much nearer A than B (the feeble disturbance 
reaching B was negligible). The resulting response 
was upward and the recovery took place in about sixty 
seconds. 

Fic. 26.-—Dr1arnasic VARIATION 
(2) Stimulus was next applied near B. The resulting 
response was now downward (fig. 26, 0). 
(3) The stimulus was now applied near the approxi- 
mately neutral point N. In this case, owing to a slight 
difference in the rates of propagation in the two direc- 
tions, a very interesting diphasic variation was pro- 
duced (fig. 26, c). From the record it will be seen 
that the disturbance arrived earher at A than at B. 
This produced an upward response. But during the 
