PHYSIOLOGY. 
mams, where an opening has taken place 
in that part ; yet it is necessary that the 
tympanum should communicate with the 
fauces, for an obstruction of the eustachian 
tube causes deafness. 
Vibrations may be transmitted to the 
auditory nerves through the bones of the 
head ; thus a watch placed between the 
teeth is heard very distinctly, although the 
cars are stopped, &c. 
Smelling. The odorous effluvia of bodies 
are disseminated in the atmosphere. The 
latter fluid passes through the nose in respi- 
ration, and thereby brings the odorous par- 
ticles into contact with the olfactory nerves, 
which convey the impressions of odours to 
the brain. It is in the first pair of nerves 
only tiiat the sense of smelling is supposed 
to reside, while the numerous twigs of the 
fifth pair that are distributed in the nose are 
merely for the purpose of general sensibi- 
lity. Hence we see two very distinct 
modes of sensibility in this part, one of 
which may be entirely obliterated, while 
the other is augmented ; in violent coryza 
the ordinary feeling is very acute, for the 
pituitary membrane is painfiil ; but the per- 
son at the same time is not conscious of the 
strongest odours. 
As air is the vehicle of odours, its passage 
through the nose, in ordinary respiration, is 
sufficient for the purpose of smelling ; but 
when any odour is particularly agreeably, 
we make short and repeated inspirations, 
and at the same time shut the mouth, that 
the air, which enters the lungs, may pass 
entirely through the nose. On the con- 
trary, we breathe by the mouth, or entirely 
suppress respiration when odours are un- 
pleasant to us. 
The small distance between the origin of 
the olfactory nerves in the brain, and their 
termination in the nose, renders the trans- 
mission of impressions very sudden and 
easy. This induces us to apply to the nose 
stimuli that are proper to revive sensibility 
when life is suspended, as in cases of faint- 
ing, suffocation, &c. 
Tasting. No body can affect the organ 
of taste, that is not soluble at the ordinary 
temperature of the saliva. Hence the che- 
mical maxim, “ corpora non agunt nisi 
soluta,” may be very justly applied to this 
sense. If the tongue be completely dry, and 
a body applied to it be also dry, no sense 
of taste ensues, as any one may convince 
himself by wiping his tongue dry and ap- 
plying sugar to it. The state of the tongue’s 
surface, which is well known to depend 
much on the condition of the stomach, also 
impairs our sense of taste ; hence in some 
disorders every thing tastes bitter. 
No sense approaches more nearly to 
feeling, than this does ; and the organ bears 
a considerable analogy to that of the sense 
of touch. The superior papillous surface of 
the tongue is the organ of taste, but we can- 
not deny the power of discerning savours to 
other parts of the mouth ; bitter substances 
are particularly tasted about the throat ; 
and in some instances where large portions, 
or the whole tongue have been cut away or 
destroyed, a perception of tastes has stilfre- 
mained. The lingual branch of the fifth 
pair is considered as the true gustatory 
nerve, while those sent to the tongue by the 
eighth and ninth are regarded as merely 
nerves of motion. Although the tongue ap- 
pears to be a single organ, it consists of two 
symmetrical halves; and should be consi- 
dered as a distinct right and left organ 
closely applied to each other. This is 
shewn in hemiplegia, where one-half only is 
paralysed. 
Touching, The whole surface of the skin 
is the organ of this sense, which gives us in- 
formation concerning more properties of 
extraneous bodies than any other of our 
senses. The sight, hfeariug, smell, and 
taste, are confined to circumscribed limits ; 
while the touch, distributed on the whole 
surface, effectually provide for our preser- 
vation, by giving us notice of the approach 
of external bodies, and informing us of tljeir 
properties. Every thing that is not sound, 
light, odour, or savour, is appreciated by 
this sense, as the temperature, consistence, 
dryness, or moisture, magnitude, distance, 
&c. of objects. It corrects the errors of 
sight and the other senses, of which it may 
indeed be justly termed the regulator ; and, 
above all others, furnishes us with the most 
certain and exact ideas. Exercise and cul- 
tivation bring it to a wonderful degree of 
perfection, so that in blind persons it may 
almost be said to supply the loss of sight ; in 
some such instances different colours and 
their various shades have been distinguished 
by its assistance. 
Although the tangible qualities of bodies 
can be perceived by every part of the cu- 
taneous organ, it possesses in some si- 
tuations a more delicate structure, consist- 
ing of fine pointed prominences, called pa- 
pillas, endued with greater sensibility and vas- 
cularity, and thereby constituting in a more 
especial manner organs of touch. This is 
the case with the hands. The number of 
