OF MUSCULAR MOTION. 191 



bility is not a power sin generis, as clearly different 

 from the nervous energy as from contractility. For 

 parts not muscular are not irritable, however abun- 

 dantly they may be supplied with nerves, as the corium, 

 the numerous nervous viscera ; and the muscular tex- 

 ture alone exhibits the genuine phenomena of irrita- 

 bility. So that from the weight of these united argu- 

 ments, to omit many others, it appears more just to 

 assign these phenomena to the muscular fibre alone, 

 than to ascribe them to the nerves which are common 

 to so many other parts but do not in these excite the 

 faintest sign of irritability. We say nothing of many 

 weighty arguments derived, for instance, from the 

 facts, that no proportion exists between the degree of 

 irritability and the number of nerves in any part, 

 that one description of vital powers is often very ener- 

 getic, while the other is languid in the same individual, 

 according to national, morbid, or more especially to 

 sexual variety, &c. (C) 



303. The nerves exert their influence upon the 

 muscles, as remote or exciting causes of their action, 

 but by no means as the proximate or efficient, which is 

 the inherent irritability of the muscles. 



The passions, v. e. act upon the sensorium, this upon 

 the nerves of the heart, so as to excite its irrita- 

 bility, which produces palpitation and other anomalous 

 motions. 



The will acts upon the sensorium, this reacts upon 

 the nerves of the arm, which' excite muscular motion, 

 as remote causes ; but the proximate cause is the irri- 

 tability of the muscles themselves. 



304. With this distinction of the two causes of inus- 

 eular motion, the result of tho.ss- experiments exactly 



