THE ORGANS OF SENSE. 



243 



tral spiral canal, forming on transverse section an irregular 

 triangle, with its apex directed towards the axis of the cochlea. 

 This is Reissner's cochlear canal, canalis cochlearis (Cj, the 



f\J K I < t ] 



r 



Fig. 197. — Perpendicular transverse section through the canal of the cochlea and neighborhood, in 

 an older embryonic calf ; V, scala vestibuli ; T, scala tympani ; C, canal of the cochlea ; />, 

 Reissner's membrane with -its insertion (a) into a projection at the so-called habenula sulcata (c) ; 

 b. connective tissue stratum with a vas spirale at the under surface of the membrana basilaris ; c> ', 

 teeth of the first series ; d, sulcus spiralis, with thickened epithelium, which extends as far as the 

 developing Cortian organ, f; e, habenula perforata ; C »i, Corti's membrane (1. inner thinner, 2, 

 middle thicker portion of the same, 3. its outer end) ; g, zona pectinata ; //, habenula tecta ; k, 

 epithelium of the zona pectinata ; k'. of the outer wall of the canal of the cochlea ; k", of the 

 habenula sulcata ; /, ligamentum spirale (?', transparent connecting portion of the same with the 

 zona pectinata) ; «?, entering projection ; «, cartilaginous plate ; 0, stria vascularis ; /, periosteum 

 of the zona ossea ; ^, transparent outer layer of the same ; q< bundle of the cochlear nerve ; j, 

 place of termination of the medullated nerve fibres ; /, place of the axis cylinder in the canalicula 

 of the habenula perforata ; r, tympanic periosteum of the zona ossea. 



proper cochlea of the lower groups of amphibia. Here alone, 

 at the bottom, terminates the nervus cochlearis. 



It is impossible for us to describe here the infinitely com- 

 plicated structure of the fundamental portion of this true 

 cochlea, the more so as, unfortunately, in addition to all the 



