THE LARYNX AND THE LAR 365 



is not understood. Several theories have been advanced with reference 

 to its explanation, one of the most interesting being that proposed by 

 Helmholtz. This theory is based on our knowledge of sympathetic 

 vibrations. The basilar membrane, while continuous throughout, may 

 be regarded as made up of many separate cords of different lengths 

 stretched side by side. A tone of a given pitch will set into vibration 

 only certain of these cords, while tones of different pitch will set others 

 into vibration. 



Another theory is that the basilar membrane responds to all kinds 

 of vibrations and the analysis of sound takes place in the brain. 



A third view is that the filaments from the hair cells, rather than the 

 basilar membrane, respond to the vibrations and in turn stimulate the 

 terminations of the nerve fibers. 



Hygiene of the Ear. The ear, being a delicate organ, 

 is frequently injured by careless or rough treatment. The 

 removal of the ear wax by the insertion 

 of pointed instruments has been found 

 to interfere with the natural method of 

 discharge and to irritate the membrane. 

 It should never be practiced. It is un- 

 necessary in the healthy ear thus to 

 cleanse the auditory canal, as the wax is FIG. 155. Diagram 

 passed by a natural process to where showing how wax may 



. , , , , , plug the auditory canal 



it is easily removed by a damp cloth. ^ n( f cause deafness . 

 If the natural process is obstructed, 

 clean warm water and a soft linen cloth may be employed 

 in cleansing the canal, without likelihood of injury. Clean 

 warm water may also be introduced into the auditory 

 canal as a harmless remedy in relieving inflammation of 

 the auditory canal and of the middle ear. Children's ears 

 are easily injured, and it goes without saying that they 

 should never be pulled nor boxed. 



It frequently happens that a mass of wax collects in the 

 auditory canal and closes the passage so completely as to 



