CHAPTER II. 



SOURCE OF ORGANIC ENERGY. CONSTITUTION OF 



MATTER. ACTION OF FORCES UPON LIVING MAT- 

 TER. 



In considering the problems of living matter, it 

 must never be forgotten that we are studying but 

 a subdivision of science, and that the limited range 

 of phenomena which we have before us forms but 

 a portion arbitrarily selected from the great body 

 of natural phenomena. From this great body of 

 phenomena have been drawn certain fundamental 

 generalisations which by a vast preponderance of 

 evidence are shown to be universally applicable as 

 laws. We must therefore believe that biological 

 phenomena, as well as all others, are governed by 

 these laws, unless it can be definitely proven that 

 biological phenomena are excepted from their general 

 application. 



Biology is bordered on one side by the science of 

 physics, and on the other side by psychology ; so 

 that the laws discovered in these two branches of 



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