. Quain's elements of anatomy . these spaces also exist, but in the special form of twotubular prolongations, one of which is situated on each side (above andbelow) of the cochlear canal, representing the first form of the scalavestibuli and scala tympani. Of these lymph passages the upper com-mmiicates with the vestibule, but the lower or scala tympani, which issomewhat later in being formed, is closed at the fenestra rotunda. Thescalffi gradually progress along the coils of the cochlear canal till theyreach its summit or cupola, which at first adlieres to the wall of the this, h
. Quain's elements of anatomy . these spaces also exist, but in the special form of twotubular prolongations, one of which is situated on each side (above andbelow) of the cochlear canal, representing the first form of the scalavestibuli and scala tympani. Of these lymph passages the upper com-mmiicates with the vestibule, but the lower or scala tympani, which issomewhat later in being formed, is closed at the fenestra rotunda. Thescalffi gradually progress along the coils of the cochlear canal till theyreach its summit or cupola, which at first adlieres to the wall of the this, however, it is afterwards separated, when the two scalte,having arrived at the summit, communicate with each other and inter-vene between the cupola and capsular wall. THE EAK. 853 The lagma of the uncoiled cochlea of birds corresponds to the cupolaof the cochlear canal in mammals. The lamina spiralis, with the organ of Corti and the upper and lowerseparating membranes (membrane of Reissner and membrana basilaris), are Fig. Fig. 762. — Transveese section op THi: COCHLEA IN A FlETAL CALF, MAGNIFIED. (FroDi Kollikcr.) C, the wall of the cochlea, stillcartilaginous; cc, canalis cochlea;;Is, placed in the tissue occupying theplace of the scala vestibuli, indicatesthe lamina spii-alis; 7), the centralcochlear nerve ; g, the place of thespiral ganglion; S, the body of thesphenoid; cli, remains of chorda dor-salis. afterwards gradually developedoutwards from the central pillarof the coiled cochlea; but wecannot attempt to give any detailed account of the formation of these minute aud intricate struc-tures. It may, however, be mentioned that the auditory nerve when firstformed is of large size and pierces the auditory capsule in two main divi-sions, vestibular and cochlear. The latter is remarkable as having uponit at an early period a large ganglion which exists before the cochleabecomes coiled, but which, being developed along with the lamina spiralis,takes the same coiled for
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