54 OF VITAL MOTION. 



peculiar; and if not these, we have to ask if it be 

 electricity? That it may be so we may argue for 

 many reasons, but especially from the history of the 

 blade electrometer, where the metal leaflets are seen 

 to diverge on the communication of the influence which 

 they are intended to measure, and to collapse when 

 touched phenomena so singular that we are led to 

 ask if the instrument is not a coarse and clumsy imi- 

 tation of the leaf of the sensitive plant. It is not diffi- 

 cult to suppose indeed that this leaf, of whose extreme 

 susceptibility to motion we have evidence, may be a 

 natural electrometer , and also that it may become 

 charged with electricity, for it is acted upon by light 

 and heat and other forces, with which electricity is 

 associated as a correlative agent. It is also difficult 

 to believe otherwise than that something has been ab- 

 stracted, and not communicated, when the plant is 

 touched, for we have evidence in the undisturbed 

 natural changes of the plant that contraction is con- 

 sentaneous with the withdrawal of the diurnal stimulus, 

 while at the same time the possibility of an instanta- 

 neous abstraction, and the production of similar re- 

 sults, is evident in the movement of the common 

 electrometer, so that this very fact of sudden contrac- 

 tion is a strong argument in favour of the force con- 

 cerned being of the nature of electricity. 



In this manner we may fancy the sensitive plant to 

 be an exquisitely delicate natural electrometer adapted 



