OF VITAL MOTION. 93 



parted. Indeed, the presumption in favour of the 

 latter hypothesis had the advantage, inasmuch as the 

 state of contraction under other circumstances was 

 seen to be expressive of a change of this character. 

 In voluntary muscles, also, the same arguments hold 

 good, for so far as we have gone we have been able to 

 trace the operations of a common law of action ; but 

 here also are found other arguments in favour of the 

 same view, in the presence of an actual electrical 

 condition of the parts, the equilibrium of which may 

 be disturbed by the contact of any foreign body. 



Under these circumstances, it may be presumed that 

 the effects of mechanical irritation are more intelli- 

 gible on the presumption of a stimulus having been 

 abstracted than the reverse ; and from the known elec- 

 trical condition of the part it may be said that there 

 is a process of discharge at the instant of contact, just 

 as is the case on touching a charged electrometer, and 

 that the process of contraction in the one case is a 

 phenomenon analogous to the collapse of the metal 

 blades in the other. 



That there is an actual discharge of this kind 

 during mechanical irritation we may further argue 

 from the intimate analogy which exists between a 

 mass of muscle and the organ which produces free 

 electricity in certain fishes, as the Torpedo and 

 Gymnotus. Owen, Faraday, and Matteucci have all 

 contributed important arguments in proof of this 



