The Variation of Animals and Plants under DomesticationNote 52 — Chapter XXIII · DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE.Reading editionMr. B. D. Walsh, ibid., p. 633, and Dec. 1866, p. 275.◇Copy noteReturn to CHAPTER XXIII. DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE.