CHAPTER XVI 



PHILOSOPHICAL QUESTIONS AND THE 

 TREND OF PHYSIOLOGY 



143. IN the brief survey we have given of 

 physiological processes, questions of a philo- 

 sophical nature cannot have failed to occur 

 to the mind. There is one always keenly 

 debated, namely, the existence of a vital force 

 or energy, as distinguished from the physical 

 forces with which we are acquainted. It does 

 not serve any practical purpose either to 

 deny or to affirm the existence of such a 

 force. As a matter of fact, we are met every- 

 where with phenomena which cannot be 

 explained by our present knowledge of physi- 

 cal and chemical science. Numerous in- 

 stances of such phenomena have been pointed 

 out, and it is surely scientific and philosophical 

 to recognize the limits of our knowledge. With 

 the progress of science we may, and indeed 



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