-1878J MISCELLANE01 



fear I .shall not he able to give any assistance to Book 111. 1 Letter 557 

 1 think I formerly gave my few criticisms, but I will r< 

 it over again very soon (though I am striving to finish 1 

 S. American Geology 3 ) and see whether I can give you any 

 references. I have been thinking over the subject, and can 

 remember no one book of consequence, as all my materials 

 (which arc in an absolute chaos on separate bits of paper) 

 have been picked out of b not directly treating of the 



subjects you have discussed, and which I hope some day to 

 attempt; thus Hooker's A ntarctic Flora 3 I have found emi- 

 nently useful, and yet I declare I do not know what precise 

 facts I could refer you to. Bronn's Geschichte ' (which you 

 once borrowed) is the only systematic book I have met with 

 on such subjects ; and there are no general views in such 

 parts as I have read, but an immense accumulation of refer- 

 ences, vc 1 y useful to follow up, but not credible in themselves : 

 thus he gives hybrids from ducks and fowls just as readily 

 as between fowls and pheasants ! You can have it again 

 if you like. I have no doubt Forbes' essay, 6 which is, I 

 suppose, now fairly out, will be very good under geographical 

 head. Kolreuter's German book u is excellent on hybrids, 

 but it will cost you a good deal of time to work out any 

 conclusion from his numerous details. With respect to varia- 

 tion I have found nothing — but minute details scattered over 

 scores of volumes. But I will look over Book III. again. 

 What a quantity of work you have in hand! I almost wish 

 you could have finished America, and thus have allowed 

 yourself rather more time for the old Principles ; and 1 am 

 quite surprised that you could possibly have worked your 



1 This refers to Hook III. of the Principles — " Changes of the Organic 

 World now in Progress." 



'-' Geological Observations on South America was published in 1 



3 Botany of the Antarctic Voyage oj ' H. M.S. " E 

 in iiic Years 1839-43. !• Flora Antarctica. 2 vols., London, 1844 



1 Naturgeschichte der drei Reiche. 11. E. Bronn, Stuttgart, 1834-49. 



; ' "On the Connection between the Distribution of the existing Fauna 

 and Flora of the British Isles, and the Geological Changes which have 

 affected their Area, especially during the Epoch of the Northern Drift," 

 by E. Forbes. Memoirs of Geological Survey^ Vol. I., p. 336, 1S46. 



6 Joseph Gottlieb Kolreuter's Vorlaufig hricht von eininigen 



das Geschlecht der Pjlanzcn betreffenden Wrsuchcn und 1- .->/• 



Leipzig, 1 761. 



