i860.] AUSTRALIAN FLORA. 259 



from Australia to New Zealand, and therefore floatation seems 

 the only possible means ; but yet I maintain that we do not 

 know enough to argue on the question, especially as we do 

 not know the main fact whether the seeds of Australian 

 orders are killed by sea-water. 



The discussion on European Genera is profoundly interest- 

 ing ; but here alone I earnestly beg for more information, viz. 

 to know which of these genera are absent in the Tropics of 

 the world, i.e. confined to temperate regions. I excessively 

 wish to know, on the notion of Glacial Migration, how much 

 modification has taken place in Australia. I had better 

 explain when we meet, and get you to go over and mark 

 the list. 



.... The list of naturalised plants is extremely interest- 

 ing, but why at the end, in the name of all that is good and 

 bad, do you not sum up and comment on your facts ? Come, I 

 will have a sneer at you in return for the many which you will 

 have launched at this letter. Should you have remarked 

 on the number of plants naturalised in Australia and the 

 United States under extremely different climates, as showing 

 that climate is so important, and [on] the considerable 

 sprinkling of plants from India, North America, and South 

 Africa, as showing that the frequent introduction of seeds is 

 so important ? With respect to " abundance of unoccupied 

 ground in Australia," do you believe that European plants 

 introduced by man now grow on spots in Australia which 

 were absolutely bare ? But I am an impudent dog, one must 

 defend one's own fancy theories against such cruel men as 

 you. I dare say this letter will appear very conceited, but 

 one must form an opinion on what one reads with attention, 

 and in simple truth, I cannot find words strong enough to 

 express my admiration of your essay. 



My dear old friend, yours affectionately, 



C. DARWIN. 



S 2 



