Blind Alleys 99 



relics. There are men — and women, too — who can move 

 their ears, although the accomplishment is not considered 

 of great moment in cultured circles. The three muscles on 

 each side that make this movement possible are identical in 

 detail with muscles found in other mammals, and used by 

 these other animals with greater assurance and to better pur- 

 pose. We cannot account for these muscles if we assume 



**.« ^ 



Fig. 28. Some Curious but Useless Relics 



In the glass snake, a kind of lizard {Anguis fragilis) , the buds of the 

 front legs are present during an early stage of development, a, but 

 the fully formed animal is footless. In the porpoise {Phoccena communis) 

 the buds of the hind legs or flippers are present during an early stage of 

 development, b, but the fully developed animal has only the front flippers. 

 From Gruenberg, Biology and Human Life, published by Ginn & Company. 



that the structure as a whole was designed for man's use. 

 We can account for them if we assume that the structure 

 is the result of ages of modification of an ancient heritage. 



Blind Alleys 



More familiar to most of us is the famous vermiform 

 appendix, which the general public discovered a generation 

 ago as the seat of fashionable illness. This appendix (Fig. 

 29) is a blind sac near the beginning of the large intestine. 

 It corresponds in structure and location to a part of the in- 



