2 Trans. Acad. Set. of St. Louis 



understood. The activating agent which is to be trans- 

 ferred to the nerve ending in terms of impulse, 

 must be applied directly to the nerve ending 

 or to the cells which overlie the nerve ending. 

 This statement holds for the sensations of touch, of 

 pressure, of smell and of taste. We also recognize 

 that heat is transmitted through various substances 

 which may intervene between the source of the 

 energy and the part which perceives the sensation. 

 Therefore when the end organ is affected by the energy 

 which arises from the object rather than by the object 

 itself, we are dealing with distance rather than contact 

 organs. The end organ resolves the energy, not the ob- 

 ject, in terms of code message. We do not see heat; we 

 feel it. We do not feel light rays; we see them. It 

 would therefore follow as a matter of good logic, that 

 we do not see or feel energy in the form of sound; we 

 hear it. 



Sound, next to heat, is the most difficult form of ener- 

 gy to deal with satisfactorily. From an experimental 

 point of view it is the most difficult form of energy to 

 analyze. The reason for this is easily grasped. In so far 

 as sense organs are concerned, they are crude physical 

 instruments when compared with the scales for measur- 

 ing pressure, the thermometer for measuring tempera- 

 ture, or the photographic plate for measuring light. 

 However when it comes to sound the reverse is true. 

 All physical instruments for registering sound are ex- 

 tremely crude when compared with the human ear. In 

 fact no instrument for measuring sound has yet been 

 devised which does not have a human ear on one end of 

 it. The phonodeik of Miller presents an instrument of 

 great delicacy but with a limited range of registration. 



We are likely to visualize the working of an ear much 

 in the same manner as we visualize the operation of an 

 eye by comparing it with some well-known physical ap- 

 paratus. Bearing in mind the reservations in the pre- 



