The Variation of Animals and Plants under DomesticationNote 19 — Chapter XXIII · DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE.Reading editionPrichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 155.◇Copy noteReturn to CHAPTER XXIII. DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE.