94 University of California Publications in Anatomy V'^^^- ^ 



evidence is only indirect: the higher links of the central auditory 

 path including the auditory radiation investigated in the present 

 study, in so far as they convey auditory sensations to the cortex of the 

 forebrain, bear, on the whole, the character of a "spatial" organiza- 

 tion (although much detailed study remains to be done here; see my 

 papers, 1926 and 1927). 



At any rate, any theory of hearing which would favor a ' ' diffuse 

 action of the auditory system, the latter working as a "whole," and 

 would put the entire burden of sound analysis on the cerebral cortex 

 (comparable to the purely "dynamic" concept of Gestalt psycholo- 

 gists), would unavoidably contradict the established morphological 

 facts on the innervation of the inner ear, and would be difficult to 

 reconcile with what we now believe to be some innate properties of 

 the neuroplasm. (The total number of single, individual stimuli which 

 can be transmitted by a motor nerve in a given time unit is limited by 

 the duration of the refractory period, besides other factors, and does 

 not, according to Lillie, exceed 500 in a second. No reasons exist to 

 suppose a different action in auditory neurons.)^ Since no "figures" 

 are imaginable in a conducting system wholly homogeneously organ- 

 ized, the only way to explain the minute processes in hearing appears, 

 therefore, to be to accept a kind of structural and functional differen- 

 tiation of the whole auditory system into portions of unequal 

 functional significance, as postulated by the theory of Helmholtz. 



The morphological data on the nervous supply of the cochlea in my 

 previous studies exceed, however, the requirements of Helmholtz' 

 theory. These concern especially the course of the external spiral fibers 

 of the papilla basilaris (see my paper, 1927 ; cf . especially Tello, 1931 ) . 

 It is evident that these must have some special significance for the act of 

 hearing. This and other characteristics of the auditory system, which 

 speak in favor of a regular "spatial" arrangement of the neurons 

 conducting auditory impulses toward the cortex of the forebrain. 



1 Gildemeister (p. 302) came to a similar conclusion with respect to the 

 acoustic nerve. Wever and Bray, however, found in their recent experiments 

 on action currents of the auditory nerve of the cat, a frequency as high as 

 4100 per second. According to them the auditory nerve is an exception from 

 all other nerves. Before being regarded as conclusive, these experiments which 

 contradict all previous experiences and seemingly substantiate the "telephone 

 theory of hearing" advanced by Eutherford and similar theories, must be 

 tested for possible sources of error other than those already considered by 

 the authors themselves. These may be changes of the potential m the inner 

 ear owing to the vibrations of the endo-perilymph together with those of the 

 membrana basilaris and mcmbrana tectoria, changes occurring only as long as 

 the normal conditions are maintained and ceasing soon after the death of 

 the animal. (Compare also Adrian, Jour. Physiol., vol. 71; and Davis and Saul). 



