1 6 THE STORY OF THE LIVING MACHINE. 



entirety the doctrines of the conservation of en- 

 ergy and evolution. Plainly if it should be found 

 that the energy of animate nature was not cor- 

 related with other forms of energy, this would 

 demand either a rejection or a complete modifi- 

 cation of our doctrine of the conservation of en- 

 ergy. If an animal can create any energy within 

 itself, or can destroy any energy, we can no longer 

 regard the amount of energy of the universe as 

 constant. Even if that subtile form of force which 

 we call nervous energy should prove to be uncor- 

 related with other forms of energy, the idea of 

 the conservation of energy must be changed. It 

 is even possible that we must insist that the still 

 more subtile form of force, mental force, must be 

 brought within the. scope of this great law in 

 order that it be implicitly accepted. This law has 

 proved itself strictly applicable to the inanimate 

 world, and has then thrust upon us the various 

 questions in regard to vital force, and we must 

 recognize that the real significance of this great 

 law must rest upon the possibility of its applica- 

 tion to vital phenomena. 



No less intimate is the relation of these prob- 

 lems to the doctrine of evolution. Evolution tries 

 to account for each moment in the history of the 

 world as the result of the conditions of the mo- 

 ment before. Such a theory loses its meaning 

 unless it can be shown that natural forces are suf- 

 ficient to account for living phenomena. If the 

 supernatural must be brought in here and there 

 to account for living phenomena, then evolution 

 ceases to have much meaning. It is undoubtedly 

 a fact that the rapidly developing ideas along the 

 above mentioned lines of dynamical biology have 

 been potent factors in bringing about the adop- 



