154 Irving Hardesty 



characters and then to base explanations of the phenomena, many of 

 which may be largely psjx-hic, upon the results of the application of 

 excellent mathematics and physics to the structures assumed. The 

 resonance theory must depend essentially upon the character it assumes 

 for its vibratory mechanism. Therefore the anatomical objections to it 

 must deal with these assumed characters. Among these objections may 

 be enumerated the following: 



(1) Supposing the basilar membrane to be composed of individual 

 fibers capable of vibrating independently, its environment in the lamina 

 spiralis is such that its vibration in response to many of the transferred 

 sound waves, and certainly with any degree of sensitiveness, seems very 

 improbable. The basilar membrane, the fibrous portion of the spiral 

 lamina, is closely invested by two continuous layers of tissue on each of its 

 sides. On its tympanic side, there is first the layer of endothelium lining 

 the scala tympani (see Fig. 7), and second, the much thicker layer of 

 epithelioidal cells which contains further, that anastomosing plexus of 

 blood vessels known as the vas spirale, which is only approximately a 

 single vessel in the end of the basal coil, but which elaborates with 

 increasing complexity toward the apex of the cochlea. On its vestibular 

 side, it is covered first by a "homogeneous" and well developed membrana 

 propria of the neuro-epithelium (see A"on Ebner, loc. cit., page 927, Fig. 

 1450), and lasth', the whole is covered by, or supports, the neuro- 

 epithelium including that comprising the thick organ of Corti. Outside 

 the animal body, structures of such relative thickness adhering through- 

 out to a system of strings would effectually damp at least their resonant 

 vibration. Further, if the basilar membrane were vibratory in the 

 degree supposed by the theory, the circulatory pulsations in the vas 

 spirale would very probably tend to at least confuse agitations produced 

 by resonant vibrations of its directly overlying fibers, even with the 

 habitual neglect by the auditory apparatus of the blood pulsations them- 

 selves. 



(2) The resonance theory requires, and, truly, the earlier pictures of 

 it assume (ISTeuel, "72, for example), that the basilar membrane be 

 composed of a single set of radially disposed fibers. Ayers, '91, describes 

 it in man as composed of four layers of fibers, three of which run 

 radially from the lamina spiralis ossea into the ligamentum spirale to 

 terminate at the base of the stria vascularis, and the fourth, a thin 

 layer, running at right angles to the other three. If these four layers 

 exist, there is nothing to be observed in either sections or teased prepa- 



