452 GEOGRAPHICAL DISTRIBUTION [Chap. VI 



Letter 343 P. major, Loltum perenne. All these are seeding freely. Now 

 I remember, years and years ago, your discussing with me 

 how curiously easily plants get naturalised on uninhabited 

 islands, if ships even touch there. I remember we discussed 

 packages being opened with old hay or straw, etc. Now 

 think of hides and wool (and wool exported largely over 

 Europe), and plants introduced, and samples of corn ; and I 

 must think that if Australia had been the old country, and 

 Europe had been the Botany Bay, very few, very much fewer, 

 Australian plants would have run wild in Europe than have 

 now in Australia. 



The case seems to me much stronger between La Plata 

 and Spain. 



Nevertheless, I will put in my one sentence l on this head, 

 illustrating the greater migration during Glacial period from 

 north to south than reversely, very humbly and cautiously. 



I am very glad to hear you are making good progress 

 with your Australian Introduction. I am, thank God, more 

 than half through my chapter on geographical distribution, 

 and have done the abstract of the Glacial part. . . . 



Letter 344 To J. D. Hooker. 



Down, March 30th, 1859. 

 Many thanks for your agreeable note. Please keep the 

 geographical MS. till you hear from me, for I may have to 

 beg you to send it to Murray ; as through Lyell's intervention 

 I hope he will publish, but he requires first to see MS. 2 



1 Origin of Species, Ed. 1., p. 379. Darwin refers to the facts given 

 by Hooker and De Candolle showing a stronger migratory flow from north 

 to south than in the opposite direction. Darwin accounts for this by the 

 northern plants having been long subject to severe competition in their 

 northern homes, and having acquired a greater "dominating power" 

 than the southern forms. "Just in the same manner as we see at the 

 present day that very many European productions cover the ground in 

 La Plata, and in a lesser degree in Australia, and have to a certain extent 

 beaten the natives ; whereas extremely few southern forms have become 

 naturalised in any part of Europe, though hides, wool, and other objects 

 likely to carry seeds have been largely imported during the last two or 

 three centuries from La Plata, and during the last thirty or forty years 

 from Australia." 



3 The Origin of Species; see a letter to Lyell in Life and Letters, II. 

 p. 151. 



