450 GEOGRAPHICAL DISTRIBUTION [Chap. VI 



Letter 342 Behring Straits. Do you not consider so many more seeds 

 and plants being taken from Europe to America, than in a 

 reverse direction, would go some way to account for compara- 

 tive fewness of naturalised American plants here ? Though I 

 think one might wildly speculate on European weeds having 

 become well fitted for cultivated land, during thousands of 

 years of culture, whereas cultivated land would be a new home 

 for native American weeds, and they would not consequently 

 be able to beat their European rivals when put in contest 

 with them on cultivated land. Here is a bit of wild theory ! ' 



But I did not sit down intending to scribble thus ; but to 

 beg a favour of you. I gave Hooker a list of species of 

 Silenc, on which Gartner has experimentised in crossing : 

 now I want extremely to be permitted to say that such and 

 such are believed by Mr. Benthatn to be true species, and 

 such and such to be only varieties. Unfortunately and 

 stupidly, Gartner does not append author's name to the 

 species. 



Thank you heartily for what you say about my book ; but 

 you will be greatly disappointed ; it will be grievously too 

 hypothetical. It will very likely be of no other service than 

 collocating some facts ; though I myself think I see my way 

 approximately on the origin of species. But, alas, how 

 frequent, how almost universal it is in an author to persuade 

 himself of the truth of his own dogmas. My only hope is 

 that I certainly see very many difficulties of gigantic stature. 



If you can remember any cases of one introduced species 

 beating out or prevailing over another, I should be most 

 thankful to hear it. I believe the common corn-poppy has 

 been seen indigenous in Sicily. I should like to know whether 

 you suppose that seedlings of this wild plant would stand a 

 contest with our own poppy ; I should almost expect that our 

 poppies were in some degree acclimatised and accustomed to 

 our cornfields. If this could be shown to be so in this and 



1 See Asa Gray, Scientific Papers, 1889, Vol. II., p. 235, on "The 

 Pertinacity and Predominance of Weeds," where the view here given is 

 adopted. In a letter to Asa Gray (Nov. 6th, 1862), published in the Life 

 and Letters, II., p. 390, Darwin wrote: "Does it not hurt your Yankee 

 pride that we thrash you so confoundedly? I am sure Mrs. Gray will 

 stick up for your own weeds. Ask her whether they are not more honest 

 downright good sort of weeds." 



