CHAP, ii.] THE BRAIN. 1007 



of both their hemispheres sufficiently to enable us to judge 

 whether they, like the frog, the bird and the rabbit, can carry out 

 coordinate bodily movements in the absence of the hemispheres, or 

 whether in them this part of the brain, so largely developed, has 

 usurped functions which in the lower animals belong to other 

 pints. Our knowledge is largely confined to the experience that 

 when in a dog the cerebral convolutions are removed piecemeal 

 at several operations, the animal may be kept alive and in good 

 health for a long time, many months at least, even after these 

 parts of the brain have been reduced to very small dimensions, 

 and that under these circumstances, the animal is not only able 

 to carry out with some limitations his ordinary bodily movements, 

 but also exhibits a spontaneity obviously betokening the possession 

 not merely of a conscious volition but of a certain amount of 

 intelligence. Unless we are willing to believe that a mere 

 fragment so to speak of the hemispheres can take on most 

 extended powers, such an experience seems to shew that in the 

 dog as in the rabbit and in the bird, the development of so-called 

 higher functions is not limited to the cerebral hemispheres, that 

 the middle and lower portions of the brain in the higher animals 

 as compared with the lower do not increase in bulk merely as the 

 instruments of the hemispheres, but like the hemispheres acquire 

 more and more complex functions. We may perhaps go so 

 far as to ask the question whether the volition and intelligence 

 which such a dog exhibits is not as much the product of the 

 parts lying behind the hemispheres as of the stump left in the 

 front. 



If we can thus say little about the condition of a dog without 

 the cerebral hemispheres we can say still less about the monkey, 

 which in all matters touching the cerebral nervous system serves 

 as our best, indeed our only guide for drawing inferences concern- 

 ing man ; but in all probability the monkey in this respect bears 

 somewhat the same relation to the dog that the dog bears to the 

 bird. 



In short, the more we study the phenomena 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 intelligence but up to 

 this there is none.' 



This however is not the question with which we are now 



dealing. What we want to point out is that in the higher 



animals, including at least some mammals, as in the frog, after 



the removal of the cerebral hemispheres, even though conscious 



F. 64 



