... I am HEARTILY glad you are taking up the Distribution of Plants in New Zealand, and suppose it will make part of your new book. Your view, as I understand it, that New Zealand subsided and formed two or more small islands, and then rose again, seems to me extremely probable... When I puzzled my brains about New Zealand, I remember I came to the conclusion, as indeed I state in the 'Origin,' that its flora, as well as that of other southern lands, had been tinctured by an Antarctic flora, which must have existed before the Glacial period. I concluded that New Zealand never could have been closely connected with Australia, though I supposed it had received some few Australian forms by occasional means of transport. Is there any reason to suppose that New Zealand could have been more closely connected with South Australia during the glacial period, when the Eucalypti, etc., might have been driven further North? Apparently there remains only the line, which I 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 bu-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" ("Mr. Dyer in 'Charles Darwin,'" "Nature Series", 1882, page 39.)--an intercourse 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 correspondence. 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."] CHARLES DARWIN TO T. RIVERS. (The late Mr. Rivers was an eminent horticulturist and writer on horticulture.) Down, December 28 [1866?]. My dear Sir,