[198c] Principles of Psychology, I., 447.
[198d] Ibid, p. 452.
[198e] Mental Evolution in Animals, p. 130
[217] Nineteenth Century, Nov. 1878, p. 826.
[218] Encyclopedia Britannica, Art. Biology, 9th ed., Vol. 3, p. 689.
[220a] Professor Huxley, Encycl. Brit., 9th ed., Art. Evolution, p. 750.
[220b] “Hume,” by Professor Huxley, p. 45.
[220c] “The Philosophy of Crayfishes,” by the Right Rev. the Lord Bishop of Carlisle. Nineteenth Century for October 1880, p. 636.
[221] Les Amours des Plantes, p. 360. Paris, 1800.
[222a] Philosophie Zoologique, tom. i. p. 231. Ed. M. Martin. Paris, 1873.