loo THE POPULAR SCIENCE MONTHLY. 



THE MOTOR CENTERS AND THE WILL * 



By VICTOR nORSLEY, F. E. C. S. 



MY subject being the mechanism of the will, it might be asked, 

 "What has a surgeon to do with psychology?" To which I 

 would answer, " Everything," For, without sheltering myself behind 

 Mr. Jonathan Hutchinson's trite saying that "a surgeon should be a 

 physician who knows how to use his hands," I would remind you that 

 pure science has proved so good a foster-mother to surgery, that dis- 

 eases of the brain which were formerly considered to be hopeless, are 

 now brought within a measurable distance of the knife, and therefore 

 a step nearer toward cure. Again, I would remind you that surgeons 

 rather than physicians see the experiments which so-called Nature is 

 always providing for us — experiments which, though horribly clumsy, 

 do on rare occasions, as I shall presently show you to-night, lend us 

 powerful aid in attempting to solve the most obscure problems ever 

 presented to the scientist. 



The title I have chosen may possibly be objected to as too com- 

 prehensive ; but until we are ready to admit a new terminology, we 

 must employ the old in order to convey our meaning intelligibly, al- 

 though there may be coupled therewith the risk of expressing more 

 than we desire. Thus, when I sjjeak of the mechanism of the will and 

 the motor centers of the brain, I do not intend (as indeed must be ob- 

 vious) to discuss the existence of the so-called freedom of the will, or 

 the source of our consciousness of voluntary power. 



I shall rather describe to you first the general plan of the mechan- 

 ism which conveys information to our brain, the thinking organ ; next 

 the arrangement of those parts in it which are concerned with volun- 

 tary phenomena ; and, finally, I shall seek to show by means of experi- 

 ment that the consciousness of our existing as single beings, the con- 

 sciousness of our possessing but one will, as people say, while at the 

 same time we know that we possess a double nervous system, is due 

 to the fact that pure volition is dependent entirely on the exercise of 

 the attention which connotes the idea of singleness ; consequently, 

 that it is impossible to carry out two totally distinct ideas at one and 

 the same moment of time, when the attention must, of course, be fully 

 engaged upon each. 



I fear that, in making my argument consecutive, I shall have to 

 pass over very well-beaten paths, and so I must ask your patience for 

 a few moments while I make good my premises. The nervous sys- 

 tem, which in man is composed of brain, spinal cord, nerves, and nerve- 

 endings, is arranged upon the simplest plan, although the details of 



* Lecture delivered at the Royal Institution of Great Britain. 



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