234 Heredity. 



condition as chemistry once was when dealing with bodies sup- 

 posed to be simple. Analysis has shown that the so-called primi- 

 tive sensations are themselves composite. For the analysis of these 

 sensations we refer the reader to recent treatises on psychology, 

 giving here only a single example. 



We take some sensation usually esteemed irreducible; for in- 

 stance, that of a musical note. It is known that if we cause a 

 body to vibrate, and that the vibrations do not exceed sixteen in 

 the second, we perceive a regular succession of identical sensations, 

 of which each is a separate and distinct sound. But if the vibra- 

 tions grow more rapid, these sounds, instead of being each 

 apprehended as a separate state of consciousness, blend into one 

 continuous consciousness, and that is the musical note. If the 

 rapidity of the vibrations be increased, the quality of the sound 

 varies, becoming sharper; and if the rapidity goes on steadily 

 increasing, it becomes at length so sharp that soon it becomes 

 inappreciable as sound. Nor is this all ; the researches of Helm- 

 holtz have shown that the differences of tone between instruments 

 (as the violin, the horn, and the flute) are owing to the fact that 

 different harmonies are added to the fundamental note. These 

 differences of sensations, known as differences of tone, are there- 

 fore due to the simultaneous integration of other series, having 

 other degrees of integration, with the original series. In plainer 

 terms, the fusion of these primary noises in a single state of 

 consciousness produces the sensation of a musical note ; and this 

 fusion, combined with the principal note of other less intense 

 vibrations, produces differences of tone. 



This analysis, summary and insufficient as it is, will enable us 

 to understand how illusory is the apparent simplicity of the phe- 

 nomenon we call sensation. The same is to be said of colours, 

 tastes, odours, and in general of all sensations, though with some 

 of them the analysis could not be carried so far. 1 If, then, 

 sensation is a composite phenomenon, it may, perhaps, be pos- 

 sible to discover its primary element. 



The most recent work written on this subject is Herbert 



1 For details, see Helmholtz' Physiological Optics (Lehre von der Toncmpfin- 

 dung) ; Herbert Spencer, Principles of Psychology, 60. 



