Text: The external auditory canal is about 1 1/4 inch long; rather less than the external half is formed of cartilage or gristle, the remainder in bone. Its direction is not directly inwards, but slightly forwards also. It is closed at its inner end by the "membrana tympani" or membrane of the drum. The glands which secrete the wax (ceruminous glands) are situated in the cartilaginous part of the canal, and agree in their structure with the sweat glands. The middle ear or tympanum is separated from the external ear by the membrana tympani which inclines outwards, making an angle of 45° with the floor. It is a cavity which is not shut off from the air, for the "Eustachian Tube" forms a communication between it and the pharynx, the upper part of the cavity of the throat. In the tympanum are situated three small bones, the Malleus, Incus, and Stapes, the names being derived from their shape. The malleus (hammer) has a round head and a handle and from the base of the head a thin spike of bone, the "processus gracilis" projects. The Incus (anvil) is more like a tooth with two fangs, a long and a short one. The long process carries a knob or tubercle which is originally a separate bone, as it remains in some animals through life. The stapes (stirrup) is just like a stirrup. It is very difficult to understand the arrangement of these little bones from description or even from drawings, a model or actual objects being almost necessary. The cavity of the tympanum is practically enlarged by communicating with the "Mastoid Cells", air cavities which occupy the mastoid process of the temporal bone, that process of bone which may be felt behind and below the pinna, and is supposed by phrenologists to be the residence of "Pugnacity", though they have never explained the connection between that propensity and the function which these air-cells really discharge, that of increasing the tympanic cavity. The internal ear or labyrinth is the essential part of the organ. It consists of two parts, a bony cavity enclosed in the thickness of the base of the skull, and a membranous sac within this.

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