18431882] GLACIAL PERIOD 479 



Fuchsia, etc. I cannot make out what Hooker does believe ; Letter 364 

 he seems to admit the former cooler climate, and almost in 

 the same breath to spurn the idea. To retort Hooker's 

 words, "it is inexplicable to me" how he can compare the 

 transport of seeds from the Andes to the Organ Mountains 

 with that from a continent to an island. Not to mention the 

 much Beater distance, there are no currents of water from 



o * 



one to the other ; and what on earth should make a bird fly 

 that distance without resting many times ? I do not at all 

 suppose that nearly all tropical forms were exterminated 

 during the cool period ; but in somewhat depopulated areas, 

 into which there could be no migration, probably many 

 closely allied species will have been formed since this period. 

 Hooker's paper in the Natural History Review^- is well worth 

 studying ; but I cannot remember that he gives good grounds 

 for his conviction that certain orders of plants could not 

 withstand a rather cooler climate, even if it came on most 

 gradually. We have only just learnt under how cool a 

 temperature several tropical orchids can flourish. I clearly 

 saw Hooker's difficulty about the preservation of tropical 

 forms during the cool period, and tried my best to retain 

 one spot after another as a hothouse for their preservation ; 

 but it would not hold good, and it was a mere piece of 

 truckling on my part when I suggested that longitudinal belts 

 of the world were cooled one after the other. I shall very 

 much like to see Agassiz's letter, whenever you receive one. 

 I have written a long letter ; but a squabble with or about 

 Hooker always does me a world of good, and we have been at 

 it many a long year. I cannot understand whether he attacks 

 me as a wriggler or a hammerer, but I am very sure that a 

 deal of wriggling has to be done. 



To J. D. Hooker. Letter 365 



Down, July 30th [1866], 



Many thanks about the lupin. Your letter has interested 

 me extremely, and reminds me of old times. I suppose, by 



do not exist in the low intervening hot countries" {Origin, Ed. vi., 



P- 336). 



1 Possibly an unsigned article, entitled " New Colonial Floras " (a 

 review of Grisebach's Flora of the British West Indian Islands and 

 Thwaites' Enumeratio Plantaritm ZeylanicB}. Nat, Hist. Review, Jan. 

 1865, p. 46. See Letter 184, p. 260. 



