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RESPONSE OF PETIOLE-PULVINUS PREPARATION 81. goes on for a length of time. The isolated specimen, gene rally speaking, attains a uniform sensibility after a few FIG. 31-Variation of excitability after section. (1) Immediate effect; (2) variation of excitability in a second specimen during 50 hours: (a) response 4 hours after section; (b) response after 24 hours; (c) after 49 hours. Up-line of record represents responsive fall of the leaf, down-line indicates recovery from excitation. hours, which is maintained, with very slight decline under constant external conditions, for about 24 hours. On the third day the fall of excitability is very rapid, and the sensibility declines to zero in about 50 hours after isolation
