[54] To Romanes, May 29, 1876, More Letters, vol. I, p. 364.
[55] To Fox, May, 1832, Life, vol. I, p. 206.
[56] To Henslow, May 18, 1832, Life, vol. I, p. 208.
[57] To Henslow, August 15, 1832, More Letters, vol. I, p. 9.
[58] Journal, August 29, 1858, vol. XI, p. 137.
[59] Journal, December 4, 1856, vol. IX, p. 158.
[60] Life, vol. I, p. 368.
[61] Worms, p. 97.
[62] Origin, p. 105.
[63] In Popular Science Monthly, April, 1909, vol. LXXIV, p. 198.