78 RESPONSE IN THE LIVING AND NON-LIVING 
be desired as to the effect of the reagent, we can 
obtain it by alternate stimulation of the A and B ends. 
Both ends will then show the given change. I give 
below a record of responses given by two ends of leaf- 
stalk of turnip, stimulated alternately in the manner 
described. The stalk used was slightly conical, and 
owing to this difference between the A and B ends the 
responses given by one end were slightly different from 
those given by the other, though the stimuli were 
he 
Before t After 
Fic. 47.—Apoxirion or Response aT BoTH A AND B ENDS By THE ACTION 
or NaOH 
Stimuli of 30° vibration were applied at intervals of one minute to A and B 
alternately. Response was completely abolished twenty-four minutes after 
application of NaOH. 
equal. A few drops of 10 per cent. solution of NaOH 
was applied to both the ends. It will be seen how 
quickly this reagent abolished the response of both 
ends (fig. 47). 
Effect of dose.—It is sometimes found that while a 
reagent acts as a poison when given in large quantities, 
it may act as a stimulant in small doses. Of the two 
following records fig. 48 shows the sheht stimulating 
