i 885-] On the Recognition of Noises: 341 
sions, and blows, the more continuous noises, rustling, mur- 
muring, . &c., and we must ask if they necessitate the 
assumption of special nerves ? 
In the roaring of the sea and the rustling of the wind 
among trees there occur very many small explosive noises 
and blows. We can sometimes hear them separately when 
we stand quite close to a tree through whose leaves the wind 
is passing. Along with these small blows there are in 
rustling also sounds of friction. These, in respect to the 
sound-waves, seem to bear the same relation as do the small 
irregular waves of a brook flowing among stones to the 
waves wnich arise on the surface of a sheet of water. Ac- 
cording to our former observations it does not seem 
necessary to assume special nerves for the perceptions thus 
called forth. 
Plissing is principally distinguished from rustling by the 
single noises being of a higher pitch and following more 
closely upon each other. Breathing and blowing represent 
the faintest irregular motions ol the air perceptible by our 
hearing, and are also occasioned by fridtion. 
None of these sensations compel us to assume separate 
nerves for their perception after we have once recognised 
that we perceive momentary noises, explosions, and blows, 
by transient excitement of a larger or smaller part of our 
sound-nerves. 
In order to explain the manifold charadter of these sensa- 
tions, we have a sufficient basis in the varying wave-lengths 
and amplitudes of the single impulses ; also in their greater 
or less irregularity, in their quicker or slower succession, in 
their configuration, and, lastly, in the secondary waves 
which the first impulse produces by resonance, e.g., on 
blowing into an empty bottle held before the mouth. 
Still, on the other hand, the question arises whether, al- 
though we hear noises with our sound-hearing nerves, there 
may not be also nerves with which we hear noises but not 
sounds. These would have to be nerves which, on account 
of the peculiarity of theirterminals, are not in connection with 
any sympathetic tissue, and have not the power of summing 
up impulses. Nerves exist to which this part might be 
ascribed, but there are physiological difficulties which, 
according to Briicke, militate against this supposition. 
