li Trans. Acad. »Vtt. uf St. Louis 



lated the so-called inoh'cular theory. The conooptioii 

 that tlu' sound pulse itself activates tlie end-or^^an fell in- 

 to disrepute as a result of the work of \(>ii lichnlioltz 

 amonj? the physicists and the modern sciiool of otoloLi^ists 

 headed hy Politzer. 



The mechanics of the direct activation theory has been 

 gone into in no little detail hy 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 li(|uid 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 tiie inner ear licjuid, 

 apart from wave length, is identical with the sound pulse 

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

 the liijuid is therefore dei)endent on the physical character 

 of the liquid and not dependent on the elasticity of the 

 bony container or the membrane of the round window. 

 In other words no nuiss shifting of licjuid occurs. The 

 scheme does not involve the element of inertia and a|>- 

 pears to fit the facts of the comj)arative anatomy. 



The entire histological picture of the end-organ may 

 be reinter])reted on the basis of the direct activation the- 

 ory. The basilar membrane insulates the end-organ from 

 sound j)ulses which might gain the sensitive epithelium 

 through the bony container. The vestibular membrane 

 limits the energy entering the cochlear duct through 



