WHAT EVOLUTION IS 57 



third in front of it. Most persons 

 have no power of motion in these 

 muscles and, in such instances, the 

 muscles may be looked upon as purely 

 rudimentary, but occasionally an in- 

 dividual will be found who can con- 

 trol them to a slight degree and who 

 can thereby move his external ear. 

 Even in such instances, however, the 

 amount of motion is extremely slight 

 compared with that seen in such 

 animals as the horse and the dog, 

 where the tube of the outer ear is 

 directed with great freedom in a 

 variety of ways and is used as a means 

 of discovering the direction of sound. 

 From the standpoint of actual useful- 

 ness, the three muscles attached to the 

 human ear are quite as rudimentary 

 as is the human vermiform appendix. 

 Well within the angle of the human 

 eye next the nose is a slight fold of 

 whitish membrane, the so-called plica 



