356 SEA-SIDE STUDIES. 



thrills, not of so pleasant a nature. Deafer than the deafest 

 adder will they remain, charm vre never so wisely. Equally 

 insensible must they be to music. Beethoven's melodious 

 thunder, Handel's choral might, Mozart's tender grace, Bel- 

 lini's languorous sweetness, are even more lost on them than 

 on the lymphatic dowagers in the grand tier, who chatter 

 audibly of guipure and the last drawing-room, while Grisi's 

 impassioned expression, and Mario's cantahile, are entranc- 

 ing the rest of the audience. The Mollusc can only perceive 

 noises. Sounds are by us separately recognisable in their 

 intensity, their pitch (or note), and their quality. The 

 Mollusc only recognises intensity — loudness. A wave of 

 sound agitates the otolithes in his ear, and their agitation 

 communicates to the ganglion a sensation of sound, loud in 

 proportion to the agitation. 



Had we no other evidence, this would suffice to show the 

 error of the vulgar conception of hearing. Sound is not 

 produced by waves of air striking the drum, these waves 

 being thence transmitted along the auditory nerve to the 

 brain ; but the waves agitate the sensory apparatus, which 

 in its turn acts upon the Sensational Centre. That is why 

 sounds are heard with painful distinctness when the sensory 

 apparatus is affected by other stimuli besides the pulsations 

 of waves of air. 



Few subjects are of greater interest to the philosophic 

 mind than the gradual complication of the organ of hearing, 

 with, of course, its proportional complication of function, in 

 the animal series. Even in human beings we see differences 

 only less considerable than those which exist between man 



