300 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



that simultaneous simple harmonic motions may in 

 our sensations fuse to a compound sound of definite 

 character (Klangfarbe). Moreover, a trained ear is 

 able to decompose a compound Klang into its simple 

 harmonic constituents. The mechanism of associa- 

 tive memory must share these peculiarities of our 

 organs for the perception of sounds. I believe that 

 what we commonly call intelligence depends partly 

 upon the development of this power of resonance of 

 the mechanism of association. 



The existence of phenomena of resonance in our 

 nervous processes may account for the fact that stim- 

 ulation of the same organ yields entirely different 

 results if we change the character or rhythm of stim- 

 ulation. Only certain sounds cause a dog to howl ; 

 only a certain way of rubbing the skin of a frog 

 causes the animal to croak. The so-called law of 

 the specific energy of the sense-organs has pushed 

 these important facts into the background and has 

 tried to convey the idea that the character of the 

 stimulation was something indifferent. Although 

 it is true that a blow on the eye gives rise to a 

 sensation of light, nobody would for one instant mis- 

 take this light-sensation for one caused by ether-vi- 

 brations. It is of course impossible to throw light 

 on this subject from the anatomy or histology of the 

 brain. But our experiences in regard to sound-sensa- 

 tions promise the possibility of an analysis of these 

 phenomena. Hermann and Mach come to the con- 

 clusion that the physical resonance-theory of Helm- 



