OF ANIMAL BODIES. 
105 
manufactured on the outside of the cheek, by the parotid 
gland, which lies between the ear and the angle of the low¬ 
er jaw. In order to carry the secretion to its destina¬ 
tion, there is laid from the gland, on the outside, a pipe 
about the thickness of a wheat straw, and about three fin¬ 
gers’ breadth in length; which, after riding over the masse- 
ter muscle, bores for itself a hole through the very middle 
of the cheek; enters by that hole, which is a complete per¬ 
foration of the buccinator muscle, into the mouth; and there 
discharges its fluid very copiously. 
V. Another exquisite structure, differing indeed from 
the four preceding instances in that it does not relate to 
the conveyance of fluids, but still belonging, like these, to 
the class of pipes, or conduits of the body, is seen in the 
larynx. [PI. XXI. fig. 1, 2.] We all know that there go 
down the throat two pipes, one leading to the stomach, the 
other to the lungs; the one being the passage for the food, 
the other for the breath and voice: we know also that both 
these passages open into the bottom of the mouth; the gullet, 
necessarily, for the conveyance of the food; and the wind¬ 
pipe, for speech, and the modulation of sound, not much 
less so; therefore the difficulty was, the passages being so 
contiguous, to prevent the food, especially the liquids, which 
we swallow into the stomach, from entering the windpipe, 
i. e. the road to the lungs; the consequence of which er¬ 
ror, when it does happen, is perceived by the convulsive 
throes that are instantly produced. This business, which 
is very nice, is managed in this manner. The gullet (the 
passage for food) opens into the mouth like the cone or 
upper part of a funnel, the capacity of which forms indeed 
the bottom of the mouth. Into the side of this funnel, at 
the part which lies the lowest, enters the windpipe, by a 
chink or slit, with a lid or flap, like a little tongue, accu¬ 
rately fitted to the orifice. The solids or liquids which we 
swallow, pass over this lid or flap, as they descend by the 
funnel into the gullet. Both the weight of the food, and 
the action of the muscles concerned in swallowing, con¬ 
tribute to keep the lid close down upon the aperture, whilst 
anything is passing; whereas, by means of its natural car¬ 
tilaginous spring, it raises itself a little as soon as the food 
is passed, thereby allowing a free inlet and outlet for the 
respiration of air by the lungs. And we may here remark 
the almost complete success of the expedient, viz. how sel¬ 
dom it fails of its purpose, compared with the number of 
instances in which it fulfils it. Reflect how frequently we 
swallow, how constantly we breathe. In a city feast, for 
