OP THE VOLUNTARY MOTIONS. 183 



286. Of the latter description are those muscular 

 motions which, although generally voluntary, take 

 place, under certain circumstances, without the know- 

 ledge of the mind or even in opposition to its en- 

 deavours. 



Thus we wink involuntarily, if a friend suddenly 

 approaches his finger to one of our eyes, though it 

 does not come in contact: the ring finger generally 

 bends if we bend the little finger. 



We often unconsciously move our limbs even while 

 sleeping soundly. 



On the contrary, some muscles which are almost 

 always obedient to the will, occasionally cease to be 

 so : an instance of this exists in the difficulty which 

 we experience in attempting to move the hand and foot 

 of the same side in different directions, and in all those 

 motions which, although voluntary and perfectly easy 

 if produced separately, are found very difficult if 

 attempted together.* 



287. Among those motions which are supposed to be 

 perfectly involuntary, no one is free from exception, 

 as far as we know, excepting the spasms of the uterus 

 during labour.f 



With respect to the motion of the heart, we have the 

 indubitable testimony of Baynard and Cheyne, that 

 they saw the famous English officer who could stop the 

 motion of his heart and arteries at pleasure. % 



* Consult Winslow, Mim. de VAc. des Sciences de Paris. 1739. 



f These are partly voluntary in some warm-blooded animal*-, as is shewn in 

 birds when sitting, which, if deprived of their eggs, are well known to lay others 

 in succession. 



X Cheyne, Treatise on Nervous Diseases, p. 307 sq. 



