572 COMPARATIVE PHYSIOLOGY. 



not at all follow that one with little capacity for tune may not 

 have the qualifications of ear requisite to make a flrst-rate elo- 

 cutionist. Following custom, we have spoken as though certain 

 defects and their opposites depended on the ear, but in reality 

 we can not, in the case of man at all events, affirm that such is 

 the case ; indeed, it seems, on the whole more likely that they 

 are cerebral or mental. Auditory discriminations seem, to be 

 equally if not more susceptible of improvement by culture than 

 visual ones, especially in the case of the young. 



A " good ear " seems to depend in no small degree on mem- 

 ory of sounds, though the latter may etgain have its bsisis in 

 the auditory end-organs or in the cerebral cortex, as concerned 

 in hearing. The necessity for the close connection between the 

 co-ordinations of the laryngeal apparatus in singing and speak- 

 ing and the ear might be inferred from the fact that many ex- 

 cellent musicians are themselves unable to vocalize the music 

 they perfectly appreciate. 



Synopsis of the Physiology of Hearing.— The ear can appre- 

 ciate dififerences in pitch, loudness, and quality of sounds, 

 though whether different parts of the inner ear are concerned in 

 these discriminations is unknown. Hearing is the result of a 

 series of processes, having their physical counterpart in aerial 

 vibrations, which begin in the end-organ in the labyrinth and 

 terminate in the cerebral cortex. We recognize conducting 

 apparatus which is membranous, bony, and fiuid. The auditory 

 nerve conveys the auditory impulses to the brain, though ex- 

 actly what terminal cells are concerned and how in originating 

 them must be regarded as undetermined. The essential part of 

 the organ of hearing is bathed by endolymph, and the pruici- 

 pal part (in mammals) is within the cochlear canal. Man's 

 power to locate sounds is very imperfect. The auditory brain 

 center (or centers) has not been definitely located. Compara- 

 tive anatomy and physiology point clearly to a progressive 

 development of the sense of hearing. 



