132 A NEW THEORY OF EVOLUTION. 



in the same caves, have fully developed eyes 

 that can see after becoming accustomed to 



light. 



According to Darwin, the inability of the 

 domestic duck to fly is the result of disuse 

 through domestication ; but then the logger- 

 headed wild duck of South America does 

 not fly. It can only flap its wings along 

 the surface of the water. 



A large proportion of the beetles in 

 Madeira have no wings, and Darwin argues 

 that the reason is because beetles of indolent 

 habits or with imperfect wings flew least, and 

 therefore were not so often carried to sea as 

 those of more active habits : thus partly by 

 disuse and partly by selection many genera 

 of beetles in Madeira became wingless. 



" But," Darwin continues, " the wings of 

 beetles that must use them to live are not 

 reduced but even enlarged, and this is com- 

 patible with natural selection." l 



Those beetles that continued to battle 

 with the wind had, it would appear, their 

 wings enlarged, and survived, although this 

 seems at variance with the preceding argu- 

 ment, and with the practice of the sailor, 

 who takes in a reef when the wind becomes 

 too strong for the safety of his craft. 



1 Origin of Species, Ed. vi., p. 109. 



