88 
WILLIAM H. BROWN 
ordinates represent the time intervals between the successive stimuli 
and the abscissas denote the average number of stimuli required to 
produce closure. 
fi/amher ofstimuJi app//et/ 6efore c/osi^re 
/ 2 3 4 S 6 7 8 9 /O // /2 /3 /'^ /S /S // /8 /S 
Fig. I. Graph showing relation between the number of successive stimuli 
necessary for the closure of the leaf of Dionaea, and the time interval separating 
the individual stimuli; data from Table VIII. 
This graph shows at once that the number of stimuli required for 
complete closure of the leaf is not proportional to the length of time 
intervening between the successive stimuli, excepting with time inter- 
vals of from 2 to 4 minutes; this portion of the curve, and this portion 
only, has a slope of approximately 45°. With time intervals of from 
20 seconds to 2 minutes the curve is less steep (or more nearly hori- 
