THE WONDERS OF LIFE 



"tones" or notes; when a number of tones together 

 (fundamental and over-tones) excite a complex sensa- 

 tion, we have "timbre." The vibrations of the sounding 

 body are borne to the auditory cells, which represent 

 the terminal extensions of the auscultory nerve. The 

 specific sensation of hearing can, therefore, be traced 

 originally to the sense of pressure, from which it has 

 been evolved. As the organ of hearing is, like the eye, 

 one of the principal instruments of the higher mental 

 life, and as the refined musical hearing of civilized man 

 is often taken to be a metaphysical power of the soul, it 

 is important to note that here again the starting-point 

 was purely physical — that is to say, it can be traced to 

 the sense of pressure of matter, or gravitation. 



The great importance of electricity as an agency in 

 nature, both organic and inorganic, has only lately been 

 fully appreciated. Electric changes are connected with 

 many (if not, as is now supposed, with all) chemical and 

 optical processes. Man himself and most of the higher 

 animals have no electric organs (apart from the eye), 

 and no sense-organs that experience a specific electric 

 sensation. It is probably otherwise with many of the 

 lower animals, especially those that develop free elec- 

 tricity, such as the electric fishes. The larvas of frogs 

 and embryos of fishes, if put in a vessel of water through 

 which a galvanic current is sent, place themselves when 

 it is closed with their longitudinal axis in the direction 

 of the current, with the head directed to the anode and 

 the tail to the cathode (Hermann). Again, the luminous 

 sea-animals which cause the beautiful phenomenon of 

 the illumination of the sea, and the glow-worms and 

 other luminous organisms, have probably an unconscious 

 feeling of the flow of electric energy associated with 

 these phenomena. Many plants show a direct reaction 

 to electric stimuli; when, for instance, we send a con- 

 stant galvanic current for some time through the points 



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