Early Letters 



an ideal absurdity put forth when such a simple hypothesis 

 will explain all the facts. 



I have been much gratified by a letter from Darwin, in 

 which he says that he agrees with '' almost every word " of 

 my paper. He is now preparing for publication his great 

 work on species and varieties, for which he has been col- 

 lecting information twenty years. He may save me the 

 trouble of writing the second part of my hypothesis by 

 proving that there is no difference in nature between the 

 origin of species and varieties, or he may give me trouble 

 by arri\4ng at another conclusion, but at all events his facts 

 will be given for me to work upon. Your collections and 

 my own will furnish most valuable material to illustrate 

 and prove the universal applicability of the hypothesis. 

 The connection between the succession of affinities and the 

 geographical distribution of a group, worked out species 

 by species, has never yet been shown as we shall be able 

 to show it. In this Archipelago there are two distinct 

 faunas rigidly circumscribed, which differ as much as 

 those of South America and Africa, and more than those 

 of Europe and North America : yet there is nothing on 

 the map or on the face of the islands to mark their limits. 

 The boundary line often passes between islands closer than 

 others in the same group. I believe the western part to be 

 a separated portion of continental Asia, the eastern the 

 fragmentary prolongation of a former Pacific continent. 

 In mammalia and birds the distinction is marked by 

 genera, families, and even orders confined to one region ; 

 in insects by a number of genera and little groups of 

 peculiar species, the families of insects having generally a 

 universal distribution. 



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