760 



THE EAR. 



and semicircular canals in fishes, in which they are of large size. The 

 subject still requires further research, but it appears to be pretty certain 

 from the observations of Reich, the successive papers of M. and F. E. 

 Schultze, and the corroborating observations of Kolliker, that the nerve 

 fibres break up in the transparent layer into minute ramifications, which 

 enter the epithelium and form between the epithelial cells spindle-shaped 

 nucleated bodies with elongated extremities. There have also been ob- 

 served long hair-like processes, fila acustica, projecting into the cavity, 

 beyond the epithelial surface of the ridge of the ampullse, and likewise 

 in the sacs ; and the actual continuity of these hairs with the nerve- 

 terminations has been in one instance observed by F. E. Schultze. 

 According to Lang the hairs are only the altered remains of a delicate cap 

 of tissue on the surface of the epithelium. (Kolliker's Gewebelehre, 4th 

 ed., p. 694.) 



Fig. 516. 



Fig. 517. 



Fig. 516. LEFT COCHLEA OP A CHILD SOME WEEKS OLD, opened (from Reichert). a 



The drawing was taken from a specimen which had been preserved in alcohol, and was 

 afterwards dried ; the section is made so as to show the lamina spiralis, scalas, and 

 cochlear canal in each of the three coils : the membranous spiral lamina is preserved, 

 but the appearances connected with the organ of Corti, &c., have been lost from drying. 

 / r, fenestra rotunda with its membrane ; s t, scala tympani ; s v, scala vestibuli ; I s, 

 lamina spiralis ; h t hamulus ; c c, canalis cochleae ; d, opening of the aqueductus 

 cochleae 



Fig. 517. VERTICAL SECTION OF THE COCHLEA OF A FOETAL CALF (from Kolliker). f 



In this specimen the external wall was ossified, but the modiolus and spiral lamina 

 were still cartilaginous ; the section shows in each part of the cochlear tube the two 

 scalaa with the intermediate canalis cochleae and lamina spiralis ; the radiating lines in 

 the modiolus indicate the passage of the auditory nerves towards the spiral lamina. 



COCHLEA. The membranous cochlea has the form of a three-sided 

 tube, the canalis membranacea, interposed between the scala vestibuli 

 and the scala tympani. The peripheral wall of this canal is formed by 

 part of the osseous cochlea, and on its other sides it is bounded by the 

 basilar membrane and membrane of Reissner respectively, while at its 

 inner angle is a structure named limbus laminae spiralis, and in its interior 

 resting on the basilar membrane, is the organ of Corti with the membrana 

 tectoria covering it. Each of these parts requires description. 



The membrana basilaris, or lamina spiralis membranacea, is stretched 

 across from the free margin (labium tympanicum) of the osseous lamina to 



