Chapter Ii: the Thinker

To Bates, November 22, 1860, More Letters, vol. I, p. 176.

To Fawcett, September 18, 1861, More Letters, vol. I, p. 195.

More Letters, vol. I, p. 93.

Life, vol. I, p. 40.

Answer to questionnaire, Life, vol. II, p. 355.

Life of Huxley, vol. I, p. 521.

To Wallace, August 28, 1872, Life, vol. II, p. 346.

To Balfour, September 4, 1880, More Letters, vol. II, p. 424.

Beagle Journal, p. 378.

To Wallace, December 22, 1857, Life, vol. I, p. 465.

Journal, March 23, 1853, vol. V, p. 45.

Gray to Canby, July 14, 1874, Gray, Letters, vol. II, p. 649.

Gray to Darwin, July 21, 1863, Gray, Letters, vol. II, p. 509.

Life, vol. I, p. 79.

To Fox, March 24, 1859, Life, vol. I, p. 506.

Life, vol. I, p. 83.

To Hooker, February, 1846, More Letters, vol. I, p. 56.

To Wallace, February 26, 1867, Life, vol. II, p. 276.

Grammar of Science, p. 38.

To Huxley, December 2, 1860, Life, vol. II, p. 147.

To Hooker, November 15, 1855, More Letters, vol. I, p. 84.

To Gray, November 29, 1859, More Letters, vol. I, p. 126.

Beagle Journal, p. 443.

Life, vol. I, p. 83.

Thiselton Dyer, in Life, vol. II, p. 431.

To Gray, 1857, More Letters, vol. II, p. 252.

To Hooker, January 11, 1844, More Letters, vol. I, p. 39.

To Wallace, May 1, 1857, Life, vol. I, p. 454.

To Carpenter, November 19, 1859, Life, vol. II, p. 19.

To Huxley, May 27, 1865, Life, vol. II, p. 228.

Aristotle, Historia Animalium, Book I, chapter VI.

Life, vol. I, p. 126.

To Hooker, April 14, 1855, Life, vol. I, p. 415.

To Hooker, March 26, 1863, More Letters, vol. I, p. 474.

Genetics and Eugenics, p. 181.

De Vries, Species and Varieties, p. 769.

Different Forms of Flowers, p. 156.

To Gray, April 3, 1860, Life, vol. II, p. 90.

Zur Naturwissenschaft, Einzelne Betrachtungen und Aphorismen,