XXIX.J THE PHYSIOLOGY OP MIND, 39 



Being itself unconscious, its seat cannot be in the nerves 



of consciousness ; and I think all analogy is in favour of 



the hypothesis that the currents of thought are formed in Nerves of 



the nerve-fibres that connect the different parts of the* ougit. 



ganglionic substance of the cerebrum with each other ; or, 



in other words, that thought is 'due to the mutual action of 



the ganglionic substance of tlie cerebral hemispheres, and 



the nerve-fibres that connect the different parts thereof 



It is a very significant fact, that "it is on the very large 



proportion which the commissural fibres [or those which I 



regard as the nerves of thought] bear to the rest, that the 



bulk of the cerebriim of man and of the higher animals 



appears chiefly to depend ; and it is easy to conceive that 



this condition has an important relation with the operations 



of the mind, whatever be our view of the relative functions 



of different parts of the cerebrum."^ 



If my reasoning is assented to thus far, there can be 

 little difiiculty in identifying the nerves of will. "VVe find Nerves of 

 a set of nerve-fibres which by their position serve to con- 

 nect the ganglionic matter of the cerebrum with the corpora 

 striata, which are the motor ganglia for consensual motions. 

 Analogy points to these fibres as the probable channel by 

 which determinations of will, formed in thought, are 

 conveyed to the motor organs. 



I will here anticipate a possible difficulty. "What is the Ideo- 

 physiological distinction between ideo-motor actions (to ^i^,°[{^ar 

 use Dr. Carpenter's expression) and voluntary ones ? Sup- actions : 

 pose, for instance, that I decide, on deliberation, to draw tiu^Iuished. 

 back from a position of danger, and do so ; this is voluntary 

 action. Suppose, on the contrary, that I do not wait to 

 deliberate, but itivoluntarLly shrink back from the thought 

 of danger, perhaps contrary to my better judgment ; this 

 is an ideo-motor action, and differs from a consensual one 

 only in the feeling that prompts it being not sensation but 

 consciousness of thought. The stimulus to ideo-motor 

 actions, and the stimulus to voluntary actions, both proceed 

 originally from thought, and consequently from the nerves 

 of thought. But the stimulus to voluntary action comes 

 * Cai'penter's Human Pliysiology, p. 577. 



