XL 



DEDUCTION. GENERAL INSTANCES. 



IT has been said that a large proportion of 

 Darwin's special investigations were started 

 as deductions from the general theories of 

 descent and natural selection for the purpose 

 of corroborating or testing them, and otherwise 

 working out their consequences. But before 

 turning to these it will be well to notice a 

 piece of deductive work not connected with 

 those theories; for it is important, both on 

 account of his using it himself as an illustra- 

 tion of his method and on account of the more 

 recent views that have arisen in opposition 

 to it. 



The hypothesis concerning the formation of 

 coral reefs took its rise as a special application 

 of the general rule that depositions are made 

 over sinking areas to the coral limestones of 

 the west coast of South America. 



The main outlines of his work on coral 

 islands were deductive, and so were many of 

 the special investigations of details. He spoke 



