240 SPREAD OF EVOLUTION. [1866. 



think you suggested, of sunken islands from New Caledonia. 



Please remember that the Edwardsia was certainly drifted 



there by the sea. 



I remember in old days speculating on the amount of life, 



i.e. of organic chemical change, at different periods. There 



seems to me one very difficult element in the problem, 



namely, the state of development of the organic beings at each 



period, for I presume that a Flora and Fauna of cellular 



cryptogamic plants, of Protozoa and Radiata would lead to 



much less chemical change than is now going on. But I have 



scribbled enough. 



Yours affectionately, 



Ch. Darwin. 



[The following letter is in acknowledgment of Mr. Rivers' 

 reply to an earlier letter in which my father had asked for 

 information on bud-variation : 



It may find a place here in illustration of the manner of 

 my father's intercourse with those " whose avocations in life 

 had to do with the rearing or use of living things " * — an in- 

 tercourse which bore such good fruit in the ' Variation of 

 Animals and Plants.' Mr. Dyer has some excellent remarks 

 on the unexpected value thus placed on apparently trivial facts 

 disinterred from weekly journals, or amassed by correspond- 

 ence. He adds : '' Horticulturists who had .... moulded 

 plants almost at their will at the impulse of taste or profit 

 were at once amazed and charmed to find that they had been 

 doing scientific work and helping to establish a great theory."] 



C. Darwin to T. River s.\ 



Down, December 28 [1866?] 



My dear Sir, — Permit me to thank you cordially for 

 your most kind letter. For years I have read with interest 



* " Mr. Dyer in 'Charles Darwin,'" Nature Series, 18S2, p. 39. 

 \ The late Mr. Rivers was an eminent horticulturist and writer on 

 horticulture. 



