ELECTRICAL PHENOMENA AND METABOLISM OF ARUM SPADICES. 477 



PLATE VIII. 





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Experiment 8. — Bean seedling (December II, 1907). 



' Diphasic ' response to mechanical excitation (compression) at a distance of 8 cm. 

 from the led-off region. This plant gave no response to thermic excitation. 



In the next experiment on the same plant mechanical excitation was followed by 

 a monophasic response. 



PLATE X. 



PLATE IX. 



Experiment 9.— Same plant. 



' Monophasic ' response to mechanical 

 excitation 4 cm. from the led-offl region. 

 At this distance thermic stimulation was 

 followed by a small response with an ap- 

 parent latency of 20 sees. This, if a true 

 instance of transmitted excitation, gives a 

 speed value of 2 mm. per second. 



Kxperiment 10. — Bean saedUng. 



Electrometer record of the local re. 

 sponse to localised mechanical excita- 

 tion, by a blow from a lever fixed to an 

 electromagnet, the shadow of the lever 

 being cast on the same plate as that of 

 the electrometer so as to signal the 

 instant of excitation. The local response 

 exhibits no appreciable lost time. 



