1844—1858] CROSSING 51 



To J. D. Hooker. 1 Letter 19 



Down [1845 — 1846]. 

 I am particularly obliged for your facts about solitary 

 islands having several species of peculiar genera ; it knocks 

 on the head some analogies of mine ; the point stupidly never 

 occurred to me to ask about. I am amused at your anathemas 

 against variation and co. ; whatever you may be pleased 

 to say, you will never be content with simple species, " as 

 they are." I defy you to steel your mind to technicalities, 

 like so many of our brother naturalists. I am much pleased 

 that I thought of sending you Forbes' 2 article. I confess I 

 cannot make out the evidence of his time-notions in distribu- 

 tion, and I cannot help suspecting that they are rather vague. 

 Lyell preceded Forbes in one class of speculation of this kind : 

 for instance, in his explaining the identity of the Sicily Flora 

 with that of South Italy, by its having been wholly upraised 

 within the recent period ; and, so I believe, with mountain- 

 chains separating floras. I do not remember Humboldt's fact 

 about the heath regions. Very curious the case of th^. 

 broom ; I can tell you something analogous on a small scale. 

 My father, when he built his house, sowed many broom-seeds 

 on a wild bank, which did not come up, owing, as it was 

 thought, to much earth having been thrown over them. 

 About thirty-five years afterwards, in cutting a terrace, all this 

 earth was thrown up, and now the bank is one mass of broom. 

 I see we were in some degree talking to cross-purposes ; when 

 I said I did [not] much believe in hybridising to any extent, 

 I did not mean at all to exclude crossing. It has long been a 

 hobby of mine to see in how many flowers such crossing is 

 probable; it was, I believe, Knight's 3 view, originally, that 



1 Sir J. D. Hooker's letters to Mr. Darwin seem to fix the date as 

 1845, while the reference to Forbes' paper indicates 1846. 



3 E. Forbes' celebrated paper Memoirs of the Geological Survey of 

 Great Britain, Vol. I., p. 336, 1846. In Lyell's Principles, 7th Ed., 

 1847, p. 676, he makes a temperate claim of priority, as he had 

 already done in a private letter of Oct. 14th, 1846, to Forbes {Life of 

 Sir Charles Lyell, 1881, Vol. II., p. 106) both as regards the Sicilian 

 flora and the barrier effect of mountain-chains. See Letter 20 for a 

 note on Forbes. 



3 See an article on "The Knight-Darwin law" by Francis Darwin 

 in Nature, Oct. 27th, 1898, p. 630. 



