i64 NATURE AND MAN. 



III. 



THE AUTOMATIC EXECUTION OF VOLUNTARY 



MOVEMENTS. 



[From an article on Todd's " Physiology of the Nervous System," in the 

 British and Foreign Medico-Chirurgical Review, January, 1850.] 



Every one who has attentively considered the nature of what we 

 are accustomed to call vohmtary action has been struck with the 

 fact that the will simply determines the result, not the special 

 movements by which it is brought about. If it were otherwise, we 

 should be dependent upon our anatomical knowledge for our 

 power of performing the simplest movements of the body. 

 Again, there are very few cases in which we can single out any 

 individual muscle, and put it into action independently of others ; 

 the cases in which we can do so are those in which a single 

 muscle is concerned in producing the result, as in the elevation 

 of the eyelids, and we then really single out the muscle and cause 

 it to contract, by " willing " the result. Thus, then, however 

 startling the position may at first appear, we have a right to affirm 

 that the will cannot exert any direct or immediate power over the 

 muscles; but that its determinations are carried into effect 

 through the intermediation of some mechanism, which, without 

 any further effort on our own parts, selects and combines the 

 particular muscles whose contractions are requisite to produce 

 the desired movement. This conclusion, at which we arrive by 

 an analysis of our own consciousness is in perfect harmony with 

 the influences which we should draw from the anatomical rela- 

 tions of the cerebrum ; for we have found strong reason to believe 



