206 RESEARCHES ON IRRITABILITY OF PLANTS 



time-difference in the number of dots in the two records. 

 On counting we find the difference to be 28 spaces, each 

 representing one-twentieth of a second. That is to say, the 

 time difference is actually 1/4 second, precisely what was 

 inferred from theoretical considerations. 



Effects of Ascending and Descending 

 Induction-Shocks 



In the case of animal tissues, single induction-shocks of 

 moderate intensity are known, as regards polar action, to be 



Fig. 1 10. — Records showing time-difference between re- 

 sponses due to ascending and descending induction- 

 shocks. Distance between two electrodes 5 mm. ; 

 upper record with kathode nearer the pulvinus. 

 Vibrating recorder 20 D.V. 



effective at the commencement and not at the termination 

 of the current. Hence excitation here, as in the case of 

 constant current, takes place at the kathodic region. In 

 the case of plants also I find the same to hold good. The 

 exciting electrodes from an induction-coil were placed on 

 two points on the petiole, separated from each other by 

 5 mm. Two records were taken with single induction- 

 shocks of intensity 2, now in descending and afterwards in 

 ascending directions. In the first or upper of these records 

 (fig. no) the proximal electrode was the kathode ; in the 

 lower, the kathode was distal. It will be seen from these 

 two experiments that if it be the kathode which excited 



