APPENDIX I 285 



grains are merely manufactories , set up by the pro- 

 toplasm for the purpose of obtaining stores of 

 physical energy. It is therefore to locomotion that 

 we must turn, in order to study the fundamental 

 characteristics of life. 



Now, locomotion is recognised by the spontaneity 

 of its movements ; by which we mean that they take 

 place, either independently of an external stimulus, 

 or, if in obedience to an external stimulus, they do 

 not respond to that stimulus uniformly. In other 

 words, in vital movements, action and reaction are 

 not equal and opposite. Of course, living beings are 

 subject to certain physical laws, in which action and 

 reaction are equal and opposite ; but the distinctly 

 vital movements are an addition to these, and it is 

 just this addition which constitutes the difference 

 between the facts of physics and the facts of 

 physiology. 



But when we say that locomotion is the charac- 

 teristic of life, w r e must remember that the word 

 " life " has two distinct meanings. When we have 

 wrung the neck of a fowl we say that it is dead ; but 

 when we cut a rosebud oft a tree we say that it is 

 still alive, and will live for some hours or days, until 

 the tissues dry up. But with the fowl we have 

 merely stopped the action of the nervous system , and 

 the tissues remain alive, as in the rose, for some 

 time, until they die for want of nourishment. That 

 higher life in the fowl is called somatic life. We 

 find it in all the higher animals, and in a modified 

 form in the lower animals and plants ; and it is 

 evidently quite different from the tissue or cellular 



