BIOLOGY IN RELATION TO OTHER NATURAL SCIENCES. 455 



purpose of these investii;atious has been to lU'teiiuiiie with tlie utmost 

 attainable x^recisi tlie nature of psychical relations. Some of these 

 investigations begin with those simpler reactions which more or less 

 resemble those of an automatic mechanism, proceeding to those in 

 which the resulting action or movement is moditied by the influence of 

 auxiliary or antagonistic conditions, or changed by the sinuiltaneous 

 or antecedent action on the reagent of other stimuli, in all of which 

 cases the effect canbe expressed quantitatively; others lead to results 

 which do not so readily admit of measurement. In pursuing this 

 course of inquiry the physiologist finds himself as he proceeds more 

 and more the coadjutor of the psychologist, less and less his director; 

 for whatever advantage the former may have in the mere technique of 

 observation, the things with which he has to do are revealed only to intro- 

 spection, and can be studied only by methods which lie outside of his 

 sphere. I might in illustration of this refer to many recent experi- 

 mental researches — such, for example, as those by which it has been 

 sought to obtain exact data as to the physiological concomitants of 

 pleasure and of pain, or as to the influence of weariness and recupei^a- 

 tion, as modifiers of i)sychological reactions. Another outwork of the 

 mental citadel which has been invaded by the experimental method is 

 that of memory. Even here it can be shown that in the comx)arison of 

 transitory as conq^ared with permanent memory — as, for exam])le, in 

 the getting off by heart of a wholly uninteresting series of words, with 

 subsequent oblivion and reacquisition — the labor of acquiring and reac- 

 quiring maybe measured, and consequently the relation between them, 

 and that this ratio varies according to a simple numerical law. 



1 think it not unlikely that the only efiect of what I have said may 

 be to suggest to some of my hearers the question. What is the use of 

 such inquiries? Experimental psychology has, to the best of my 

 knowledge, no technical application. The only satisfactory answer I 

 can give is that it has exercised, and will exercise in future, a helpful 

 influence on the science of life. Every science of observation, and each 

 branch of it, derives from the peculiarities of its methods certain ten- 

 dencies which are apt to predominate unduly. We sjieak of this as 

 specialization, and are constantly striving to resist its influence. The 

 most successful way of doing so is by availing ourselves of the counter 

 acting influence which two oi^posite tendencies mutually exercise when 

 they are sinuiltaneous. He that is skilled in the methods of introspec- 

 tion natiTially (if I may be i)ermitted to say so) looks at the same thing 

 from an opposite point of view to that of the experimentalist. It is 

 therefore good that the two should so w ork together that the tendency 

 of the exi)erimentalist to imagine the existence of nu'chanism where 

 none is proved to exist — of the i^sychologist to approach the phenomena 

 of mind too exclusively from the subjective side — may mutually correct 

 and assist each other. 



