VELOCITY OF TRANSMISSION OF EXCITATION 



449 



same specimen. The distance through which the transmis- 

 sion was observed was 27 mm. 



TABLE SHOWING VARIATIONS OF VELOCITY OF TRANSMISSION AND OF 

 AMPLITUDE OF RESPONSE WITH INCREASING FATIGUE 



Intervals of rest 



The plant fresh 

 3 minutes 

 2 minutes 

 I minute 

 minute 



It wHl thus be seen that the fatigue due to having only 

 half a minute's rest reduced the normal velocity of the 

 specimen by 18 per cent. 



The effect of intensity of stimulus on velocity of trans- 

 mission was next studied. The stimulus employed was that 

 of condenser discharge, increased intensity being obtained 

 by an increasing voltage of charge. In this way it was 

 found that velocity increased with increasing intensity 

 of stimulus. This fact is shown in the following table, 

 which gives the results of an experiment on a petiole of 

 Biophytum. 



TABLE SHOWING INCREASE OF VELOCITY WITH INCREASING STIMULUS 



Specimen I. Centripetal Transmission 

 The distance traversed by stimulus was 27 mm. 



Specimen II. Centrifugal Transmission 

 The distance traversed by stimulus was 38 mm. 



Velocity 



3-27 mm. per second 

 372 mm. ,, 

 376 mm. ,, 

 3-83 mm. ,, 



G G 



