i877.] MISCELLANEOUS BOTANICAL LETTERS. 513 



heavy rain, and the leaves of very few wild dicotyledons can 

 be here seen with drops of water rolling off them like quick- 

 silver. Whereas in my flower garden, greenhouse, and hot- 

 houses there are several. Again, are bloom-protected plants 

 common on your dry western plains .? Hooker thi?iks that they 

 are common at the Cape of Good Hope. It is a puzzle to me 

 if they are common under very dry climates, and I find bloom 

 very common on the Acacias and Eucalypti of Australia. 

 Some of the Eucalypti which do not appear to be covered 

 with bloom have the epidermis protected by a layer of some 

 substance which is dissolved in boiling alcohol. Are there 

 any bloom-protected leaves or fruit in the Arctic regions ? 

 If you can illuminate me, as you so often have done, pray do 

 so ; but otherwise do not bother yourself by answering. 



Yours affectionately, 



C. Darwin. 



C. Darwin to IV. Thiselton Dyer. 



Down, September 5 [1877]. 



My dear Dyer, — One word to thank you. I declare 

 had it not been for your kindness, we should have broken 

 down. As it is we have made out clearly that with some 

 plants (chiefly succulent) the bloom checks evaporation — 

 with some certainly prevents attacks of insects; with some 

 sea-shore plants prevents injury from salt-water, and, I be- 

 lieve, with a few prevents injury from pure water resting on 

 the leaves. This latter is as yet the most doubtful and the 

 most interesting point in relation to the movements of 

 plants. . . . 



C. Darwin to F. Miiller. 



Down, July 4 fiSSi]. 



My dear Sir, — Your kindness is unbounded, and I can- 

 not tell you how much'your last letter (May 31) has inter- 

 ested me. I have piles of notes about the effect of water 

 resting on leaves, and their movements (as I supposed) to 

 shake off the drops. But I have not looked over these notes 



