70 OF VITAL MOTION. 



hollow abdominal viscera; and here it may be said, 

 that the state of contraction is expressive of the 

 absence or dimunition of force. It was the opinion of 

 Bichat, that the closure of the pupil was occasioned, 

 not by the contraction of the mere rim, but by the 

 general dilatation of the iris ; and if this be true, then 

 the absence of light induces contraction, and its pre- 

 sence, dilatation, or whatever else we may agree to call 

 this state. And under any circumstances, there is 

 quite as much probability in this opinion as in the 

 hypothesis which at present prevails on this subject. 



Electricity, also, is directly concerned in 

 these phenomena, but it is difficult to estimate its 

 mode of operation, until we are able to study it in con- 

 nexion with the voluntary muscles. The facts which 

 more especially point to this agency, are those con- 

 tractions which happen in the coats of the alimentary 

 canal, when these are touched by any foreign body, 

 and which movements are said to be stimulated by the 

 contact. As in the case of the sensitive plant, how- 

 ever, it may be argued with an equal share of pro- 

 bability, that something has been abstracted in this 

 case, and that the contraction is the result of this 

 abstraction; and as in all those cases which have 

 already come under consideration, the phenomena of 

 contraction are connected with the withdrawal of 

 force, so also in these facts we may find a strong argu- 



