THE WONDER OF LIFE 625 



gether, but we cannot re- combine our analyses so as to 

 account for the whole. 



It is not merely what happens, but the way in which it 

 happens, that we have to consider. If we inquire into the 

 passage of digested food from the alimentary canal into the 

 blood, or the interchange of gases in the lungs, or the filter- 

 ing that goes on in the kidney, we certainly find that 

 these involve physico-chemical processes, and we detect 

 in their occurrence nothing that contradicts the principles 

 of physics and chemistry ; and yet the physico-chemical 

 formulae do not suffice for a complete description of the 

 vital function. They do not quite fit ; the living cells 

 make a difference a difference which we have at present 

 to accept as a fact. 



Every year we know more about the physical and 

 chemical processes that occur in living bodies, but it does 

 not seem as if the physico-chemical explanation of vital 

 functions was coming any nearer. We do not know what 

 the future may have in store ; but we must take things 

 as they are, and there is surely significance in the fact 

 that increased knowledge of physiological chemistry and 

 physiological physics has brought the distinctively vital 

 into stronger relief. It has not made the distinctively 

 vital more intelligible ; that is, it has not shown it to be a 

 particular instance of something more general. 



Treating the organism as a machine has led to great 

 clearness in regard to the big transformations of energy 

 that go on in the body. Without Chemistry and Physics 

 applied to the living body, what would be our understand- 

 ing of respiration, of animal heat, of muscular work, or of 

 the significance of the various kinds of waste ? And yet 

 what works well as an engine of research, does not suffice 



s 3 



