126 THE SPINAL CORD AND CEREBELLUM 



logical meaning, that in addition to the purely sensory 

 or intellectual cells others of a different type, which 

 we may call for the moment ' will ' cells, have been 

 brought into play. But it will be clear to everyone 

 that ' will ' cells in this sense must be ' increase of 

 impulse ' cells. They must, that is to say, possess 

 certain attributes or properties which enable them to 

 intensify the action of other cells, either greater size 

 and more elaborate branches, or a greater supply of 

 blood, or something of an analogous nature, by means 

 of which a sufiSciency of force may be generated to 

 augment the action of the sensory cells. It has 

 probably never been suggested that the ' will ' centre 

 is identical with the vaso-motor centre ; yet the 

 supposition, though probably not true, is nearer to 

 the truth than one might be led at first sight to 

 believe. The ' increase of impulse ' or ' will ' cells 

 act, one may expect, both indirectly on the sensory 

 cells through the vaso-motor cells and directly also. 

 The reflex — for will is certainly a reflex — may be 

 described thus : Action is started in the sensory 

 or intellectual cells of the cerebral cortex ; it causes 

 the ' increase of impulse ' or ' will ' cells to vibrate ; 

 these react on them, and at the same time transmit 

 a decided stimulus to the vaso-motor centre. The 

 result is a quickening or intensification of the whole 



The part proccss of thought or sensation. 



crease of The word ' will,' however, is often used in a way 



ceJ^rin^in- which, physiologically speaking, is not correct, or, at 



action.*"^^ least, is very liable to cause error. 



