INTBODUCTION 



ELECTRO-PHYSIOLOGY, as set forth in the following pages, com- 

 prises on the one hand the theory of the electrical excitation of 

 excitable tissues, on the other the electromotive reactions which 

 these exhibit. In order to understand the subject, an adequate 

 knowledge of the phenomena of excitation, and in particular of 

 the effects of current upon living matter, is essential, and must 

 therefore be considered in the first instance. While in Morpho- 

 logy it is a matter of course that any inquiry should proceed 

 from simple to complex, in Physiology experience and intuition 

 alike teach us that the converse is often more fertile and more 

 expeditious. This is due in part to the nature of the methods 

 at our command, in part to fundamental physiological differences 

 in the individual elements. What is morphologically simple is 

 not always physiologically intelligible ; in a sense we might rather 

 affirm the opposite. If it be true that every function of the 

 more highly - developed multicellular organism is potentially 

 nascent in the relatively undifferentiated protoplasm of the 

 amoeba, the apparent simplicity of the latter must conceal a 

 complex of physiological activities not to be compared with those 

 cases in which one kind of cell serves only one single function, 

 as a muscle-cell contraction, a gland-cell secretion, etc. 



Here we have obviously a better chance of acquiring exact 

 knowledge of the inherent qualities of the physiological function 

 in question than if we turn to primitive organisms whose proto- 

 plasm serves indifferently the most diverse functions. The study 

 of glands and gland-cells reveals more of the process of secretion 

 than the investigation of the same process in unicellular organisms, 

 and the physiology of muscle has added more to our knowledge of 

 contraction and its connected processes than we could ever have 



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