452 



COMPARATIVE ELECTRO-PHYSIOLOGY 



responses, according as the virtual inertia of the one indicator 

 exceeds that of the other. 



In determining velocity of transmission by the Electro- 

 motive Method, a previous experiment gives us the loss of 

 time due to the inertia of the galvanometer. This, deducted 

 from the observed interval between the application of 

 stimulus and response, gives the time required for trans- 

 mission through the given distance. In this manner I have 

 been able to determine the rate of transmission of excitation 

 in ordinary plants. I give below a table which shows these 

 velocities as determined by me in the case of sensitive plants, 

 and of ordinary plants, and for the purpose of comparison, 

 those obtained by other observers, in the nerves of some of 

 the lower animals, from which it will be seen that all these 

 are more or less of the same order. 



TABLES GIVING VELOCITIES OF TRANSMISSION OF EXCITATORY WAVE 



(a) Animal. 



Subject 



Velocity 



Nerve of Anodon .... 

 Nerve of Eledone (observed by Uexkiill) 



10 mm. per second 

 5 to I mm. ,, 



(b) Sensitive Plants. 



Subject 



Velocity 



Mimosa pudica : petiole 

 Neptunia oleracea : petiole . 

 Biophytum sensitivum : 



Petiole of, direction centripetal 

 Petiole of, direction centrifugal 

 Peduncle of ... 



14 mm. per second 

 I'l mm. ,, 



2'i mm. ,, 

 3-8 mm. ,, 

 37 mm. ,, 



(c) Ordinary Plants. 



