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University of California Puhlications in Anatomy [^'oi- 2 



or "radiated" fibers (orthoneura) one appears justified in attributing 

 to these the main role in the reception and transmission of acoustic 

 excitations. They will represent the path for the main current of the 

 auditory impulses centralward. The discrimination, that is, the dis- 

 tinction between two different elementary auditory sensations or tones, 

 will very probably be based, in so far as the nervous structures are 

 concerned, on the same structural principle of isolation as exists in the 



X^y-^ .-y^ 'v^ "S^ '^ 'V' 'V' T^ 'Y^ 'y~' ""Y^ 'v^ T^ IT* nr* 

 1 ^2 ^:) ^. ^5 ^6 7 "^r ^i ^E ^ ^F ^E -^m ^(D^(; 



Fig. 11. A scheme to illustrate the internal organization of the central 

 auditory path and its function. (For explanation see chapter XII.) 



visual and somato-sensory systems. As described previously, a com- 

 plete separation and isolation of the teledendra of auditory nerve 

 fibers does not exist, for these latter partly overlap each other (excep- 

 tionally there are sing-le terminating' fibers). It appears plausible, 

 therefore, that the purity of a simple acoustic sensation will depend 

 on the complete separation of two correspondingly stimulated groups 

 of hair cells, if, for instance, two pure tones are simultaneously per- 

 ceived (in our scheme fig. 11, A^ from A2, Ao from A3, and so forth). 

 In two such groups of hair cells the teledendra must not overlap. The 



