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2. J. C.Greene, ?Reflections on the Progress of Darwin Studies,? J. Hist. Biol., 8 (1975), 243?273.
3. R. M.Young, ?Darwin's Metaphor: Does Nature Select?? Monist, 55 (1971), 442?503.
4. Charles Darwin, The Origin of Species, p. 4. Unless specified otherwise, all references are to the first edition, published by John Murray in 1859.
5. FrancisDarwin, ed., The Life and Letters of Charles Darwin, 3 vols. (London: John Murray, 1887) [hereafter referred to as L & L], II, 29.