SENSE OF HEARING. 



259 



Fig. 51, 



[Fig. 52. 



Papillre of the Auditory Nerve, on a 

 Segment of the Spiral Lamina of the 

 Cochlea of a young Mouse ; the lower 

 portion is the osseous, and the higher the 

 membranous part of the lamina. Mag- 

 nified 300 times. After Treviranus. 



The Auditory Nerve taken out of the Cochlea; 1, 1, 1, the 

 trunk of the nerve ; 2, 2, its filaments in the zona ossea of the 

 lamina spiralis; 3, 3, its anastomoses in the zona vesicularis.] 



[Fig. 53. 



A highly magnified view of a small piece of the Lamina Spiralis, showing the globular structure of the 

 Nerves, and the manner in which they leave their Neurilema as they anastomose; the natural size of 

 the piece is seen on the side of the figure; 1, portion of the auditory nerve; 2, 2, osseous canals in the zona 

 ossea of the lamina spiralis; 3, 3, anastomoses in the zona mollis ; 4, 4, the neurilema leaving the nervous 

 loops and interlocking to form the layer of the zona membranacea.] 



others state that the papillae are clearly to be distinguished. The fact appears 

 to be that, as in the retina, the fibres do form a minute plexus ; but that fibres 

 are connected with this, which end, or rather commence, in papillae. The 

 auditory nerve is also very minutely distributed on the membrane lining the 

 vestibule and semicircular canals ; and in the ampullae or dilated extremities 

 of the latter, there are little projections of this membrane internally, which 

 are largely supplied with nerves. 



353. In order to gain any definite idea of the uses of different parts of 

 the Ear, it is necessary to bear in mind, that sounds may be propagated 

 amongst solid or fluid bodies in 'three ways, by reciprocation, by resonance, 

 and by conduction. 1. Vibrations of reciprocation are excited in a sounding 

 body, when it is capable of yielding a musical tone of definite pitch, and 



