PREFACE 



I HAVE been encouraged by several medical friends, and 

 particularly by my fellow students, Drs. White Robertson 

 and E. W. Martin, to make an excursion into the realm of 

 Electro-physiology ; a subject which I had previously been 

 reluctant to take up in the declining years of my life owing 

 to the controversy which any new view of the operating 

 forces of the body would be sure to provoke. But the 

 matter at issue is too important for personal considerations 

 to outweigh a possible advance in knowledge. 



For more than half a century theories which were 

 without any real scientific basis have barred the way to 

 progress, and the rebutting evidence hitherto at command 

 was in itself insufficient to compel adequate attention, 

 although it was, upon careful examination, enough to refute 

 the theories in question. 



In a former work* of an unambitious character I 

 considered the nature and distribution of nerve force from 

 a new standpoint, and it followed that if I had discovered 

 a fundamental principle my research work must harmonise 

 with established laws and enable me, in accordance with 

 those laws, to explain not only the nature and source of 

 the force but to show how by its means the various func- 

 tions of the body were called into operation. 



The two theories of the nature of the nerve' impulse, 

 the physiological and the physical, are, in the present state 

 of our acquaintance with the subject, equally unsatisfac- 

 tory; but it has always been clear to my mind that upon 

 investigation the body structure should make it manifest 

 whether it was primarily designed for electrical or chemical 

 functions ; or rather, whether it was evident from its 

 * Electro-Pathology and Therapeutics. 

 vii 



