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Updated: May 6, 2025
We have already seen that the embryonic bird has the long tail of his reptilian ancestor. In early embryonic life it has gill-slits leading from the pharynx to the outside of the neck like those through which the water passes in the respiration of fish. The Eustachian tube and the canal of the external ear of man, separated only by the "drum," are nothing but such an old persistent gill-slit.
A sudden explosion, the noise of a cannon, may burst the drum-head, especially if the Eustachian tube be closed at the time. During heavy cannonading, soldiers are taught to keep the mouth open to allow an equal tension of air. Section of Cochlea. From A straight downwards is the direction of the central column, to which E points.
The middle ear, it will be seen, is a drum with its stretched membrane like any other drum, and it too has a communication with the exterior air through a tube, the Eustachian tube, which leads from the drum into the back part of the throat.
Men who would blush if caught saying Iphigénia instead of Iphigenía, or would resent as an insult any imputation of ignorance respecting the fabled labours of a fabled demi-god, show not the slightest shame in confessing that they do not know where the Eustachian tubes are, what are the actions of the spinal cord, what is the normal rate of pulsation, or how the lungs are inflated.
It breathed first upon the left temple, and upon the upper part of the left ear; the breathing proceeded thence to the left eye, and by degrees to the right, and flowed down afterwards, especially from the left eye, to the lips; and when at the lips it entered through the mouth, and through a way within the mouth, and, indeed, through the Eustachian tube, into the brain.
It irritates and dries the mucous membrane of the mouth and throat, producing an unnatural thirst which becomes an enticement to the use of intoxicating liquors. The inflammation of the mouth and throat is apt to extend up the Eustachian tube, thus impairing the sense of hearing. But even these are not all the bad effects of tobacco.
The practice of snuffing up cold water into the nostrils is occasionally followed by an acute inflammation of the middle ear, some of the water finding its way through the Eustachian tube into this part of the organ of hearing.
This tube is rather longer, but much narrower, than the outer passage, leads inwards obliquely from the anterior wall of the tympanic cavity, and opens in the throat below, behind the nasal openings. Both the Eustachian tube and the tympanic cavity are lined with a thin mucous coat, which is a direct continuation of the mucous lining of the throat.
It is bitter to return to infancy, to be supported, and directed, and perpetually set upon your feet, by the hand of some one else. The air besides, as it is supplied to you by the busy millers on the platform, closes the eustachian tubes and keeps the neophyte perpetually swallowing, till his throat is grown so dry that he can swallow no longer.
He is said to have made extensive dissections of the lower animals, and to have described many hitherto unknown structures, such as the optic nerve and the Eustachian canal the small tube leading into the throat from the ear.
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