1 64 THE METHOD OF DARWIN. 



ought to lead to the right explanations, and 

 because he always regarded it as better to 

 work out a single typical case or a few typ- 

 ical cases thoroughly, in proof of his theories, 

 than to offer miscellaneous suggestions on 

 many cases. 



Climbing plants offered a case of special 

 importance. When once the principles of 

 descent and natural selection are adopted as 

 working hypotheses, it is a comparatively easy 

 matter to explain how a group of closely related 

 animals or plants come to possess one or more 

 striking characteristics in common. In such a 

 case they are all supposed to have inherited the 

 characters in question from a common ancestor. 

 For example, all the woodpeckers, with their 

 peculiar feet and tail and tongue, the last 

 with its remarkable apparatus of hyoid-bone 

 and muscle, or the various oaks with their 

 acorns and cupules, their flowers and leaves, 

 are believed to have descended from a com- 

 mon stock. The individuals of these groups 

 have a great many characters in common. But 

 climbing plants are found throughout the plant 

 kingdom. Some families contain several or 

 many closely related climbers, and these offer 

 no special difficulty so far as their mutual pos- 

 session of the power to climb is concerned. 



