THE EAR AND HEARING. 
119 
THE EAR AND HEARING.* 
BY W. J. ABEL, B.A., F.R.M.S. 
Sound may be described as the vibration of solids and 
fluids, propagated, by means of waves, through some inter¬ 
vening medium, to a specially prepared sentient surface. The 
function of the ear is to intercept and collect these undula¬ 
tions, and convey the result to the brain, by which organ they 
are made manifest to the individual as sound sensations. We 
may thus define the sensation of hearing as the conscious 
state resulting from the impinging, upon a specially prepared 
part of the sentient surface of the body, of aerial or other 
fluid vibrations, caused by the molecular disturbance of bodies 
in a state of tremor or vibration. Thus, in hearing, as in 
the other sensations, we take cognisance by the mind, not of 
the sonorous object, but of the condition of the auditory nerve; 
and all the ideas we form of sounds, as to their nature, 
intensity, direction, &c., must be based upon the changes 
which they produce in it. 
The essential part of an organ of hearing is obviously 
a nerve endowed with the peculiar property of receiving and 
transmitting sonorous undulations. 
Since all matter is capable of propagating sonorous vibra¬ 
tions, the simplest conditions must be sufficient for mere 
hearing, as all substances surrounding the auditory nerve 
can communicate sound vibrations to it. In the eye a 
certain disposition of parts is essential to cause the rays of 
light to impinge on the sentient surface with the same rela¬ 
tive disposition as that which they held when they left the 
visible object; but in the ear, whenever and however 
sonorous undulations affect the nerve, they must cause a 
sensation of sound. It is, therefore, by no means indispen¬ 
sable, as some assert, that any specially modified surface 
should be included in the auditory apparatus, since the 
auditory nerve if merely in contact with any solid part—as 
the head—will be affected by the vibrations in which it is 
continually participating; and we are thus unable to assert 
that the sense is present only where we can discover a special 
organ. 
The two modifications most constantly present in all 
auditory organs hitherto identified are— 
I. A cavity wholly or partially filled with fluid, and 
lined with a membrane on which the nerve is 
distributed. 
* Read before the Nottingham Naturalists’ Society, February 17, 1885. 
