128 OF MIND. 



of well ascertained facts are strongly in favour of this 

 inference.* 



But if conclusive proof had been afforded that the nerve 

 current was electricity, we should not even in that case have 

 ascertained the whole truth, and, indeed, should have 

 advanced but a little way towards a true explanation of nerve 

 phenomena. For action and work are due not to force 

 alone, but to the machinery by which the force is con- 

 ditioned, and this is determined in nerve organs by the 

 arrangement of the fibres and centres in short, by the 

 form or structure of the nerve apparatus. And this form 

 and structure are the result of a long series of changes of 

 the most complex character, which cannot be fully explained 

 in the present state of our knowledge, but can be proved 

 to be dependent upon the germinal matter ; and since it has 

 been shown that the nervous system at an early period con- 

 sists entirely of germinal matter, and that in the fully 

 developed state there is much germinal matter associated 

 with every part of it that is active, especially all nerve 

 centres and all peripheral organs, it is obvious that we can- 

 not advance one step towards the explanation until we have 

 determined the nature of the changes occurring in the 

 germinal matter. 



But unfortunately we are not yet acquainted with the 

 exact structure even of the simplest nervous apparatus. 



* It is a source of regret to me that my friend Dr. Child should 

 have so mistaken my views upon this matter, as to tell his readers 

 ("Essays on Physiological Subjects." Second edition, p. 277) that I 

 look "upon nerve force as a form of vital force," which is a view 

 contrary to that which I have taught for the last twenty years. 



