THE POSITIVE RESPONSE 187 



second. The positive response is here seen to take place 

 4 seconds, and the negative 41 seconds, after the appHcation 

 of stimulus. The negative impulse in this case lagged as 

 much as 37 seconds behind the positive. In Table III will 

 be seen the transmission-periods of positive and negative 

 impulses in different specimens of Averrhoa and Mimosa. 



Conditions Favourable for the Exhibition of Positive 



Response 



I will now describe experiments which bring out the 

 conditions which are favourable for the manifestation of 

 either the positive or the negative response : — 



I. Positive response is more easily obtained under feeble 

 stimulus. — This is demonstrated by the following experiment 



Fig. 102. — Effect of intensity of stimulus in the induction of positive or 

 negative response. Lowest record under stimulus-intensity of i, 

 middle record under 5, and the uppermost record under 8 units. 

 Vibration frequency 5 times per second. 



on Mimosa, where successive stimuli were applied at the 

 same distance on the stem, the intensity being gradually 

 increased in a known manner. The distance of application 

 was 10 mm. The vibration-frequency of the writer was 

 5 times per second. The first and the lowest record of the 

 series (fig. 102) was taken under the stimulus intensity of i. 

 It will be seen that under this relatively feeble stimulus 

 a positive or erectile response, indicative of positive turgidity 



