IX. 



ON THE DOCTRINE OF HUMAN AUTOMATISM. 



[Contemporary Review, February, 1875.] 



What is the range and limit of the Automatic action of the 

 body of Man, and what clue we gain from modern physiological 

 research as to the manner in which it is controlled and directed 

 by his mind, are the questions I propose to discuss in this 

 paper ; and it will, I think, be advantageous to enter upon the 

 discussion historically, by tracing the principal stages in the 

 development of the system of doctrine now generally accepted by 

 physiologists. 



Somewhat more than fifty years ago (1821), the publication of 

 the discoveries of Charles Bell gave a new impetus to a study which 

 had previously made but little progress for more than a century. 

 It was by him that the principle was first placed on a valid ex- 

 perimental basis, that every one of the ^multitudinous fibres of 

 which any single nerve-trunk is composed, runs a distinct course 

 between its central and its peripheral terminations ; and that its 

 function consists in establishing a connection, in the one case, 

 between an organ of sense and the central sensorium ; or, in the 

 other, between a motor centre and the muscle which it calls into 

 contraction. The fibres of the former class he termed " sensory," 

 and those of the latter " motor ; " and he showed that while the 

 ordinary spinal nerves contain fibres of both functions (separated, 

 however, into distinct groups at their roots), there are nerves in 

 the head which are sensory only, and others which are solely 

 motor. It has since been proved, however, that between these 

 two classes of nerve-fibres there is not really any essential 



