C50 



THE EAR. 



Fig. 464. 



the columnar, and are supported by them. Finally, as described 

 by Max Schultze, a layer of columnar epithelium {h) rests upon the tunica 

 propria by the broad ends of the cells, whilst the opposite, tapering 

 ends project between the other epithelial and nervous elements, which 

 they no doubt assist to support. The branches 

 of the auditory nerve («) pass directly through 

 the loose-meshed tissue above mentioned 

 and through the thickened tunica ])ropria ; 

 the fibres then lose their medullary sheath 

 and dark contour, and are continued as 

 simple axis-cylinders. Immediately before 

 reaching the epithelium each axis-cylinder 

 appears to break up or branch out into a 

 number of fine fibrils, which form a network 

 by uniting with the neighbouring fibrils 

 beneath and between the bases or attached 

 ends of the epithelium cells. With this fine 

 network the central ends of the spindle- 

 shaped cells, W'hich, as just mentioned, 

 are stated to bear at their opposite free 

 extremity the fine auditory hairs, are believed 

 to be connected. According to Rudiuger, a 

 nervous fibril passes directly through the axis 

 of each spindle-cell, and projects at the free 

 end as an auditory hair, being in its course 

 connected with the nucleus of the cell. 



An entirely different account of the relations 

 between these several elements is given by 

 Eetzius, who describes the auditory hairs 

 (fig. 4fi4, li) as being borne each by one of the 

 columnar-shaped cells, and these latter as con- 

 nected by the narrower central end {c) with, 

 and passing directly into a nerve-fibril, whereas 

 the long, slender, spindle-shaped cells {sp) 

 which project at one extremity between the 

 columnar elements, and the nucleated bodies 

 of which nre several rows deep, rest by their 

 somewhat broadened basal end upon the tunica 

 propria, and are to be regarded merely as sup- 

 porting structures for the proper nervous ele- 

 ments. According to the same observer, the 

 nerves retain their medullary sheath some little 

 way beyond the limit of the tunica propria, 

 and their axis fibres do not Ibrm an anas- 

 tomosing network, but after merely branching 

 two or three times pass directly, as just stated, into the attenuated ends 

 of the columnar cells, which he accordingly terms tlu " auditory" 

 cells. He further states that the auditory hairs are very liable to 

 break up under the influence of reagents into a bunch of more 

 delicate hairlets (A')." 

 The whole question must be regarded as at present undecided, 



* Anatomisclie UntersucliuDgen : Das GehorlalnTinth der Knochenfische, Stockliolm, 



■'S72. 



rig. 4G4. — Auditory Epi- 



THELI0JI FROM AmPULLA 



OP A Fisu (Retziu.s). 

 Highly Magnified. 



/(, auditory liairs ; li', the 

 tasal end of one broken np 

 into finer filaments ; sp, 

 spindle-cells ; c', attenu- 

 ated extremity of columnar 

 cell. 



