620 ANIMAL PHYSIOLOGY. 
have the qualifications of ear requisite to make a first-rate elo- 
cutionist. Following custom, we have spoken as though cer- 
tain 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 again have its basis 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 appreciate 
differences 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 aérial vibra- 
tions, which begin in the end-organ in the labyrinth and ter- 
minate in the cerebral cortex. We recognize conducting ap- 
paratus which is membranous, bony, and fluid. 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 princi- 
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. _ 
THE SENSE OF SMELL. 
The nose internally may be divided into a respiratory and 
an olfactory region. The latter, which corresponds, of course, 
with the distribution of the olfactory nerve, embraces the upper 
and part of the middle turbinated bone and the upper part of 
the septum, all of which differ in microscopic structure from 
the respiratory region. Among the ordinary cylindrical epi- 
