VELOCITY OF TRANSMITTED IMPULSE 141 



may be arrived at which are of great constancy. It may 

 be said of the velocity of transmission in the petiole of 

 Mimosa that it is constant with a given specimen, but 

 undergoes some variation with different individuals. It 

 is also subject to modifications induced by season. In 

 winter the velocity is much reduced. The highest velocity 

 which I have obtained with summer specimens of the 

 petiole of Mimosa is 30 mm. per second. The lowest, in 

 sluggish specimens, may be as little as 4 mm. per second. 

 The tabular statement below shows results obtained 

 in twenty-five determinations in different specimens. 

 Maximal stimulus was applied in every case. 



Table I. — Determination of Velocity of Transmission of 

 Excitation in various Specimens of Mimosa 



