THE EAR. 



placed below the columnar cells, and in many ifc is close to the central end of the 

 fibre. The fibres, which are probably sustentacular in function, like the fibres 



Fig. 125. NERVE TERMINATIONS IN 



MACULA ACUSTICA, SHOWN BY 

 GrOLGl's METHOD. (Gf. Retzius.) 



of Miiller in the retina and the 

 cells of Deiters in the cochlea, 

 expand slightly as they ap- 

 proach the free surface, and 

 appear to become attached to 

 a cuticular structure which en- 

 closes the ends of the hair-cells 

 and is thus comparable to the 

 reticular lamina of the cochlea 

 (Urban Pritchard). On the other 

 hand the fibres are set by their 

 central ends upon a limiting 

 membrane which bounds the 

 epithelium next to the tunica 

 propria, and which appears in section as a fine but well-marked line. 



Fig. 126.- 



-SECTION OF EPITHELIUM OF AMPULLA OF LACEUTA 

 VIRIDIS. (Gr. Retzius.) Magnified. 



The limit of the auditory epithelium at the sides of 

 the crest is sometimes marked, at least in the human 

 ampullae, by a prominent vessel (fig-. 123. r). 



The auditory hairs were first noticed by Max Schultze, 

 who described them as being- connected with the elongated 

 cells and not with those of a columnar shape. Their true 

 relations were pointed out by Retzius. and in this matter 

 my own observations, in the fish and in man, coincide 

 with his. When the cells are isolated after preservation 

 in osmic acid, the separated columnar cells are alone 

 surmounted by auditory hairs, whereas the elongated 

 intermediate cells are not provided with auditory fila- 

 ments. It is worthy of note that the auditory hairs do 

 not in sections made from hardened specimens appear to 

 project freely into the endolymph of the ampulla, but 

 into a soft material which takes a dome-like shape (cvpula 

 frrittina?!*. Lang), and appears to possess an indistinctly 

 fibrillar structure. If this material is pre-existent (and 

 not merely, as some have supposed, produced by a swelling 

 and alteration of the auditory hairs after death), it is not 

 possible to imagine that the hairs can be set in vibration 

 singly, but whatever movements are communicated to 

 the endolymph, must affect the whole cupula and all the 

 hairs embedded in it. 



The foregoing description of the characters of the 

 epithelium and mode of nerve-distribution in the cristae 

 acusticae of the ampullae, is equally applicable to the 

 maculae acusticae of the saccule and utricle. The nerves 



which are supplied to the maculae seem, however, to spread out more than those to the 

 ampullae. The auditory hairs are somewhat shorter than those of the ampullae. As before 

 mentioned, both saccule and utricle contain in their cavity and lying in contact with the 

 nerve-epithelium a little mass of otoliths. which, however, do not float free in the fluid, but 

 appear imbedded in a soft matrix which is perhaps enclosed in a delicate cuticular investment. 

 Otoliths are also found scattered here and there in the ampullae and semicircular canals. 



The membranous cochlea, which occupies the spirally-wound tube of the 

 osseous cochlea consists like this of about two and three-quarter turns, which 



