Art and Science 



deal, what does a good deal mean ? And what 

 is the proportion between the shares attribut- 

 able to use and disuse and to natural selec- 

 tion respectively ? If we cannot be told with 

 absolute precision, let us at any rate have 

 something more definite than the statement 

 that natural selection is " the most important 

 means of modification." 



Mr. Darwin gave us no help in this respect ; 

 and worse than this, he contradicted himself 

 so flatly as to show that he had very little 

 definite idea upon the subject at all. Thus 

 in respect to the winglessness of the Madeira 

 beetles he wrote : 



" In some cases we might easily put down 

 to disuse modifications of structure, which 

 are wholly or mainly due to natural selection. 

 Mr. Wollaston has discovered the remarkable 

 fact that 200 beetles, out of the 550 species 

 (but more are now known) inhabiting Madeira, 

 are so far deficient in wings that they cannot 

 fly ; and that of the 29 endemic genera no less 

 than 23 have all their species in this condition ! 

 Several facts, namely, that beetles in many 



parts of the world are frequently blown out to 



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