[1488] Darwin, vol. ii. p. 252.
[1489] Müller, ‘The Fertilisation of Flowers,’ p. 14.
[1490] Wallace, ‘Tropical Nature,’ p. 223.
[1491] ‘The Colours of Plants and the Origin of the Colour-Sense,’ in ‘Tropical Nature,’ pp. 221-248. ‘Darwinism,’ ch. x.
[1492] Wallace, ‘Tropical Nature,’ pp. 193-195.
[1493] Ibid., p. 187.
[1494] Wallace, ‘Tropical Nature,’ p. 213.
[1495] Idem, ‘Contributions to the Theory of Natural Selection,’ pp. 73, et seq.
[1496] Ibid., pp. 259-261.
[1497] Fraser, in ‘Nature,’ vol. iii. p. 489.