140 THE NEW PHYSIOLOGY. 



alimentary canal. The progress of physical chemistry 

 is enabling us to distinguish sharply between physio- 

 logical activity and the processes occurring in non-living 

 structures ; and the establishment of the distinction is 

 sweeping away the easy-going mechanistic explanations 

 which became current during the latter half of last 

 century. 



On the whole there is no evidence of real progress 

 towards a mechanistic explanation of life ; and those 

 physiologists who still believe that the mechanistic line 

 of attack is the right one are compelled to justify their 

 belief on general philosophical grounds. We ought, 

 they say, to advance from the simple to the complex ; 

 from the sure and familiar ground of physics and chem- 

 istry to the unknown ground of biology. Practically 

 speaking, they argue that life must be a mechanical 

 process, although at present we cannot understand the 

 mechanism. 



Now I wish to go straight to the point, and explain 

 why, as it seems to me, life cannot be regarded as a 

 mechanical process. A living organism differs in this 

 respect from any mechanism which we can construct or 

 conceive, that it forms itself and keeps itself in working 

 order and activity. Bearing this in mind, let us look 

 again at the various apparent mechanisms previously 

 referred to. The bones and muscles involved in limb- 

 movements have not only developed into the particular 

 arrangement which renders them efficient, but from hour 

 to hour and day to day nutritive activities are occurring 

 in them which keep this arrangement intact. More- 

 over, the actual movements are, apart altogether from 

 conscious interference, guided and controlled at every 



