CHAP, vi.] THE BRAIN. 613 



have hitherto done, the meaning of the words ' volition ' and ' in- 

 telligence ;' and should probably in the end come to the conclusion 

 that the discussion is a barren one. The more we study the pheno- 

 mena exhibited by animals possessing a part only of their brain, 

 the closer we are pushed to the conclusion that no sharp line can 

 be drawn between volition and the lack of volition, or between the 

 possession and absence of intelligence. Between the muscle-nerve 

 preparation at the one limit, and our conscious willing selves at 

 the other, there is a continuous gradation without a break; we 

 cannot fix on any linear barrier in the brain or in the general 

 nervous system, and say ' beyond this there is volition and in- 

 telligence but up to this there is none.' 



This however is not the question with which we are now deal- 

 ing. What we want to point out is that in the higher am' mala, 

 including mammals, as in the frog, after the removal of the cerebral 

 hemispheres (or rather of the cerebral convolutions, for interference 

 with the corpora striata and optic thai ami is apt to induce disorders 

 of which we shall speak presently), even though volition and in- 

 telligence appear to be largely, if not entirely, lost, the body is 

 still capable of executing all the ordinary movements which the 

 animal in its natural life is wont to perform, in spite of these 

 movements necessitating the cooperation of various afferent 

 impulses ; and that therefore the nervous machinery for the 

 execution of these movements lies in some part of the brain 

 other than the cerebral hemispheres. We have reasons for 

 thinking that it is situated in the structures forming the middle 

 or hind brain. 



