TIME-RELATIONS OF RESPONSE 



4i 



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 T V second in the contractile portion, and 10 

 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 

 Recovery in Leaf of Mimosa 



Response and 



Period of contraction 



,, recovery 

 Maximum rate of contractile movement 



,, ,, movement of recovery 



Average rate of contractile movement 



,, ,, movement of recovery . . 



3 seconds 

 16 minutes 

 24 mm. per second 

 •09 „ „ 

 15 

 •°45 



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 



