172 THE AUDITORY NERVE AND COCHLEA, BY W. WALDEYER. 



and in other animals (fig. 324, K). Lowenberg gives full details 

 respecting them. See also Kolliker, Mikroskopische Anatomic, p. 751. 



The pale fibres which have traversed the foramina still 

 continue to pursue their radial course, in order to reach 

 their terminal organs, and must be divided into two groups, 

 the internal and external terminal nerve fibres, correspond- 

 ing to their connection with the internal and external hair 

 cells. Both the internal and the external fibres traverse, 

 immediately after their emergence, a thin layer of small 

 roundish cells, the granule layer (figs. 331 and 335 A), 

 which is situated upon the internal slope of the organ 

 of Corti, close to the point where the nerves traverse it. I 

 shall again recur to the consideration of this granule layer, as 

 well as to its relations to the nerve fibres, when I come to 

 describe the spiral fibrous bands of the organ of Corti, and 

 now proceed to follow out the radial nerve fibres to their 

 destinations. 



The inner radial fibres, as I have on several occasions been 

 able to observe (fig. 335 B), pass directly through the granule 

 layer, and are at once continuous with the pointed extremities 

 of the internal hair cells. These fibres, as far as I can see, have 

 a relatively considerable thickness (1*5 2 //,), and I am therefore 

 disposed to regard them not as isolated axis-fibrils, but as a fas- 

 ciculus of such fibrils, that is to say, as an axis-cylinder. (See 

 vol. i., pp. 157, 158.) In regard to their diameter, they may 

 well correspond to the undivided axis-cylinder of a inedullated 

 i auditory fibre entering at the foramina nervina. Hasse (18 

 [ 25) everywhere found a similar mode of termination of the 

 nerves in the hair cells of the Bird and Frog. (See infra.) 



The external radial fibres, as Gottstein has noticed, pass 



between each couple of the internal pillars into the tunnel of 



Corti, traversing it at about the middle of the height of the 



pillars, so that they resemble stretched harpstrings when seen 



in profile. In like manner they leave the cavity of the arch 



I between the external pillars, and pass, rising a little towards 



^ the vestibule, directly to the external hair cells, with which 



they coalesce (figs. 331 and 332). In Dogs and Bats I have 



on several occasions seen this mode of termination of the 



