6 Trans. Acad. Sci. of St. Louis 



lated the so-called molecular theory. The conception 

 that the sound pulse itself activates the end-organ fell in- 

 to disrepute as a result of the work of von Helmholtz 

 among the physicists and the modern school of otologists 

 headed by Politzer. 



The mechanics of the direct activation theory has been 

 gone into in no little detail by the writer. The physics 

 is that of the string telephone and the recognition that 

 sound pulses like light rays behave differently in vari- 

 ous physical media. The drum membrane according to 

 this theory affords a sort of catchment area for minute 

 energies in the air. These energies within the mem- 

 brane flow for the most part to the most tense area, the 

 attachment of the ossicles. The ossicles behave like a 

 solid rod transmitting the energies with longer wave 

 length to the footplate area. This is widened to fa- 

 cilitate the discharge of the energy into the liquid of the 

 inner ear and is insulated from transmitting the energy 

 into the surrounding bone by an elastic annular ligament. 

 In this manner a small amount of the energy from the 

 drum membrane reaches the liquid of the inner ear as a 

 sound pulse. The sound pulse in the inner ear liquid, 

 apart from wave length, is identical with the sound pulse 

 of the air of the external auditory canal. The shiver in 

 the liquid is therefore dependent on the physical character 

 of the liquid and not dependent on tiie elasticity of the 

 bony container or the membrane of the round window. 

 In oilier words no mass shifting of liquid occurs. The 

 scheme does not involve the element of inertia and ap- 

 pears to fit tlie facts of the comparative anatomy. 



The entire histological picture of the end-organ may 

 be reinterpreted on ti»e basis of the direct activation the- 

 ory. The basilar membrane insulates tlie end-organ from 

 sound pulses whicli might gain the sensitive epithelium 

 tlirongli the bony coniaiiHjr. Tiu; vestil)ular nicTnbrane 

 liniits the energy entering the cochlear duct tlirougli 



