78 



INNEKVATION. 



[CHAP, xvm, 



surface of the osseous zone, including the denticulate lamina, is con- 

 vex, rising from the free series of teeth toward the modiolus. 



Fig. 138. Fig. 139. 



Denticulate lamina of the os- 

 seous zone of the lamina spiralis, 

 seen on the vestibular surface. 

 a Free edge of the teeth, which 

 are separated by fissures as far as 

 the line b. The clear tracts, 

 with intervening rows of globules , 

 are seen at d. e. Margin towards 

 the axis of the cochlea. From the 

 sheep. Magnified 100 diameters. 



Tympanic surface of a portion of the lamina spiralis of the 

 cat. a. Termination of the cochlear nerves at the border of the 

 osseous zone, with capillaries ramifying over them. 6 Inner 

 clear belt of the membranous zone. c. Marginal capillary on 

 the tympanic surface, d. Pectinate portion of the membranous 

 zone. The half-detached fragment on the opposite edge shows 

 its mode of tearing, e. Outer clear belt of membranous zone, 

 torn from the cochlearis muscle. Magnified 300 diameters. 



In the groove already mentioned there is a series of elongated 

 bodies, not unlike columnar epithelium, in which the nuclei are 

 very faint. These bodies are thick and cubical at one end, 

 and taper much towards the other. They are united in a row; 

 and it is possible they may have some analogy to the club-shaped 

 bodies of Jacob's membrane. We can assign them^no use. 



Continuous with the thin margin of the osseous zone is the 

 membranous zone. This is a transparent glassy lamina, having 

 some resemblance to the elastic laminae of the cornea, and the 

 capsule of the lens. A narrow belt of it next the osseous zone 

 is smooth, and exhibits no internal structure, while in the rest of 

 its width it is marked by a number of very minute straight lines, 

 radiating outwards from the side of the modiolus. These lines 

 are very delicate at their commencement, become more strongly 



