300 ZOOLOGICAL PHILOSOPHY 



animal organisation, we must say a word about its functions and the 

 faculties resulting from them. They are of four different kinds, viz. : 



1. That of instigating muscular activity ; 



2. That of giving rise to feeling or to the sensations which con- 

 stitute it ; 



3. That of producing the emotions of the inner feeling ; 



4. That, lastly, of forming ideas, judgments, thoughts, imagination,, 

 memory, etc. 



I shall endeavour to show that the functions of the nervous system 

 which give rise to these four kinds of faculties are very different in 

 character, and that they are not all performed by the animals which 

 possess this system. 



The activities of the nervous system which give rise to muscular 

 movement are altogether distinct from and even independent of those 

 which produce sensations : thus we may experience one or more sensa- 

 tions without any muscular movement ensuing, and we may set in 

 action various muscles without any resulting sensation. These facts 

 are worthy of note and they are unquestionably well-founded. 



Muscular movement cannot be executed without nervous influence ; 

 and although we do not know how this influence works, we are justified 

 by many facts in the belief that it may be by an emission of nervous 

 fluid which starts from a centre or reservoir and travels down the nerves 

 to the muscles which have to be actuated. In this function of the 

 nervous system then, the movements of the subtle fluid which works 

 the muscles take place from some centre or nucleus towards the parts 

 that have to carry out some action. 



It is not only to set the muscles in action that the nervous fluid 

 travels from its nucleus or reservoir towards the parts which have to 

 carry out movements ; this emission also takes place apparently in 

 order to assist various organs in the performance of functions, where 

 no distinct muscular movement is involved. 



Since these facts are well known I shall not dwell further upon them ; 

 but shall adopt the conclusion that the nervous influence, which 

 gives rise to muscular activity and which aids various organs in the 

 performance of their functions, works by an emission of nervous 

 fluid which travels from some centre or reservoir to the parts requiring 

 to be actuated. 



On this subject I may record a well-known fact that is relevant 

 to the matter now in hand. It is as follows : 



With regard to the nervous fluid which leaves its reservoir on its way 

 to the parts of the body, one portion of this fluid is subject to the will 

 of the individual who starts it moving, by means of the emotions 

 of his inner feeling, when stimulated by some requirement ; whereas 



