XXIX.] THE PHYSIOLOGY OF MIND. 37 



As the theory stated iii tliis chapter concerning the Grounds 

 functions of the three different sets of cerebral nerves is gtated"'^^ 

 avowedly propounded as only a hypothesis, I shall con- 

 clude by stating, more distinctly than I have yet done, 

 the evidence on which it rests. 



Even if we had no direct evidence on the subject, 

 analogy would make it impossible to doubt that every 

 nerve and every ganglion must have its own separate 

 function. But we have direct evidence : anatomy, and Functions 

 the results of experiments on living animals, combine to and motor 

 show, with tolerable distinctness, which are the nerves and nerves and 

 ganglia of sensation, and which are those of motion ; and are known. 

 the theory of reflex and consensual action is perfectly well 

 established. But these methods fail us in the inquiry Those of 

 about the functions of the cerebral nerves. We cannot gg^g^jj^j^j 

 doubt that nerves in connexion with the organs of sense nerves 

 are nerves of sensation, and that nerves in connexion with i^fJn-ed by 

 the muscles are motor nerves ; but when we come to the analogy, 

 cerebrum we have no such facts to guide us, and the 

 method of experiment cannot be applied. It is, however, 

 impossible to doubt that in the cerebrum, as in all other 

 organs, different nerve-fibres have different functions ; and 

 analogy may guide us, as I think, to a tolerable degree of 

 certainty as to what the functions are. 



Anatomy has shown that there are three distinct sets of 

 cerebral nerves, having distinct connexions. These are to Cerebral 

 be thus enumerated : — 



1. The fibres connecting the sensory ganglia with the 

 ganglionic substance of the cerebrum. I regard these as of con- 

 the nerves of Consciousness. sciousness, 



2. The fibres connecting the different parts of the 

 ganglionic substance of the cerebrum with each other. I 

 regard these as the nerves of Thought. And of thought, 



3. The fibres connecting the ganglionic substance of the 

 cerebrum with the corpora striata, which are the nervous 

 centres for motor action. I regard these as the nerves of and of 

 Will. "'^- 



As a parallel to these anatomical facts, the purely 

 psychological (or what is usually called the metaphysical) 



