664 EXPERIMENTAL PSYCHOLOGY 



the curves of variability which characterize the metabolism of the 

 body. When these laws have been worked out, the physiologist's 

 task is completed. His aim is to make known the whole system of 

 functional modes associated with the physical structures which 

 compose the living body. 



But for the psychologist these facts have in themselves no value 

 whatever. He should indeed be an eager student of the whole litera- 

 ture of physiological research because of the potential significance 

 of each new fact which is there revealed. But in no one of these, 

 however momentous its discovery be for the physiologist, is he con- 

 cerned, except in so far as it throws light upon the special and inde- 

 pendent problems with which he is engrossed. Hence the interest 

 of the psychologist is distributed in a manner wholly unlike that of 

 the physiologist among the series of physical phenomena which 

 constitutes the latter's field of investigation. For it is only such 

 parts of this system of physical changes as can be immediately or 

 mediately connected with discriminable variations in the associated 

 mental content that enter into the calculations of the psychologist; 

 though it may be at once acknowledged that as every function is 

 necessarily dependent upon some distinctive organic form, so pre- 

 sumably it is likewise correlated with a real change in the quality 

 of consciousness, even though the specific relation of the two may 

 as yet have escaped detection. The problem of the latter, therefore, 

 in so far as it is to be discriminated from that of the physiologist, is 

 the analysis of the whole system of correlations which exist between 

 these measurable physical processes and the immediately realized 

 succession of modifications which we know as the flow of conscious 

 life. 



The relation of psychology to physiology is not wholly one of 

 dependence. That science provides much of the terminology in 

 which the results of psychological investigation are expressed. 

 Moreover the complicated system of relations which physiology 

 has worked out forms an organized body of truths which not only 

 affords the symbols into which the relations of mental phenomena 

 are translated, but may also be used to direct the progress of inves- 

 tigation and to forecast the yet undetermined connections which 

 exist among associated states of mind. 



On the other hand it is likewise true that the knowledge of mental 

 functions and their relations has similarly been employed in framing 

 the representation of many physiological processes to which access 

 is difficult or impossible, and in guiding the experimentalist in his 

 researches concerning the functions of the central nervous system. 

 In much of our brain physiology constructive theory is directed 

 rather by an analysis of mental functions, such as perception, 

 speech, and memory, than by observation of the physical pro- 



