402 GEOGRAPHICAL DISTRI I! U T 1 N [Chap. VI 



L^" 3'4 To J. D. Hooker. 



Down, March 31st (1844). 



I have been a shameful time in returning your documents, 

 but I have been very busy scientifically, and unscientifically in 

 planting. I have been exceedingly interested in the details 

 about the Galapagos Islands. I need not say that I collected 

 blindly, and did not attempt to make complete series, but 

 just took everything in flower blindly. The flora of the 

 summits and bases of the islands appear wholly different ; it 

 may aid you in observing whether the different islands have 

 representative species filling the same places in the economy 

 of nature, to know that I collected plants from the lower and 

 dry region in all the islands, i.e., in Chatham, Charles, James, 

 and Albemarle (the least on the latter) ; and that I was able 

 to ascend into the high and damp region only in James and 

 Charles Islands ; and in the former I think I got every plant 

 then in flower. Please bear this in mind in comparing the 

 representative species. (You know that Henslow has described 

 a new Opuntia from the Galapagos.) Your observations on 

 the distribution of large mundane genera have interested me 

 much ; but that was not the precise point which I was 

 curious to ascertain ; it has no necessary relation to size of 

 genus (though perhaps your statements will show that it has). 

 It was merely this : suppose a genus with ten or more species, 

 inhabiting the ten main botanical regions, should you expect 

 that all or most of these ten species would have wide ranges 

 {i.e. were found in most parts) in their respective countries? 1 

 To give an example, the genus Felts is found in every country 

 except Australia, and the individual species generally range 



1 This point is discussed in a letter in Life and Letters, Vol. II., p. 25, 

 but not, we think in the Origin ; for letters on large genera containing 

 many varieties see Life and Letters, Vol. II., pp. 102-7, also in the Origin, 

 Ed. I., p. 53, Ed. VI., p. 44. In a letter of April 5th, 1844, Sir J. D. 

 Hooker gave his opinion : " On the whole I believe that many individual 

 representative species of large genera have wide ranges, but I do not 

 consider the fact as one of great value, because the proportion of 

 such species having a wide range is not large compared with other 

 representative species of the same genus whose limits are confined." 



It may be noted that in large genera the species often have small 

 ranges {Origin, Ed. VI., p. 45), and large genera are more commonly 

 wide-ranging than the reverse. 



