658 MANUAL OF HISTOLOGY. 



to it, and holding, of course, a spiral direction likewise. In cross-section 

 it is almost triangular. This is the canalis cochlearis, already mentioned 

 above ((7). Its three sides are consequently formed, below, by the lamina 

 spiralis membranacea (tympanic wall), above, by the membrane of Reissner 

 (vestibular wall), and externally by the parietes of the cochlea. Above, at 

 the hamulus, the canalis cochlearis ends in a blind sac (" Kuppelblind- 



Fig. 606. Vertical section through the tube of the coclilea and adjacent parts from a 

 foetal calf at an advanced period. V, Scala vestibuli; T, Sc. tympani; C, canal of the 

 cochlea; R, membrane of Reissner, with its attachment (a) to a projection on the so- 

 called habenula sulcata (c) ; b, connective-tissue layer, with a vas spirale on the under 

 surface of the membrana basilaris; c', teeth of the first row; d, sulcus spiralis, with 

 thickened epithelium, which extends to the organ of Corti (/), still in process of forma- 

 tion; c, habenula perforata; Cm, membrane of Corti (1, its inner and thinner; 2, its 

 middle thicker portion; 3, its external end); g, zona pectinata; h. habenula tecta; *, 

 epithelium of the z. pectinata; k', external wall of the cochlea; k" habenula sulcata; I, 

 ligamentum spirale (i, transparent portion of the same, connecting it with the zona pecti- 

 nata) ; m, slight elevation; , cartilaginous plate; o, stria vascularis; p, periosteum of 

 the zona ossea; p > , transparent external layer of the latter; q, bundles of cochlear nerve 

 fibres; s, point of termination of the meduHated nerve fibres; t, position of the axis cylin- 

 ders in the hab. perforata ; r, tympanal periosteum of the zona ossea. 



sack") (Hcnsen, Reichert), and below also practically, in a vestibular sac 

 (" Vorhofs' blind sac "), although there does exist a communication 

 between it and the sacculus rotundus (Hensen, Reichert, Henle). This 

 is a short and fine tubule, opening at right angles into the lower end of 

 the canalis cochlearis, in the same way as does the oesophagus into the 

 stomach. We name this the canalis reuniens. The latter, like the two 

 blind sacs, is only lined with cubical epithelial cells, and is destitute of 

 the acoustic nerve fibres present elsewhere. 



Both scala tympani and scala vestibuli are lined by a fibrous coat. 

 The membrane of Reissner is also formed of fibrous connective-tissue 



