TIME-RELATIONS OF RESPONSE 



41 



at intervals of 10 seconds. Fig. 14 gives us a record of 

 a response reduced to two-thirds taken in this way. It 

 will be seen that the recovery practically takes place in 

 16 minutes. Thus in the present case, while the pulvinus 

 took only 3 seconds to complete the contraction, it required 



Fig. 14. — Response of Mimosa. Successive dots are at 

 intervals of yV second in the contractile portion, and lo 

 seconds in the recovery portion of curve. Vertical marks 

 below indicate intervals of i minute. 



16 minutes to recover from it. It will be seen, further, that 

 the rate of recovery is quicker at the beginning and slower 

 at the end. The following is a tabular statement of the 

 time-relations of the different phases of response and 

 recovery : — 



Tabular Statement showing Time-relations of Response and 



Recovery in Leaf of Mimosa 



Period of contraction 



,, recovery 

 Maximum rate of contractile movement 



„ „ movement of recovery 



Average rate of contractile movement 

 „ „ movement of recovery . . 



We may now briefly recapitulate the sequence of events 

 in a typical specimen of Mimosa subjected, during the 

 summer season, to a moderate stimulus. Response does 



