[49] Loc. cit., p. 24.
[50] Address of Dr. F. A. P. Barnard, as retiring president, before the Am. Ass. for Adv. of Sci., Chicago meeting, Aug. 1868. "Thought cannot be a physical force, because thought admits of no measure."
[51] Derivation hypothesis of life and species, forming fortieth chapter of his Anatomy of Vertebrates, republished in Am. Jour. Sci., II, xlvii, 33, Jan. 1869.
[52] Prehistoric Times, p. 354, by Lubbock.
[53] Madness in Animals, Jour. Mental Sci., July, 1871. Dr. W. L. Lindsay.
[54] Facultés Mentales des Animaux, 1872, Tom. XI, p. 181.
[55] Primeval Man, 1869, pp. 145-147.
[56] Prehistoric Times, 1865, p. 473.
[57] "Conferences ser les Théorie Darwinienne," 1869, p. 132.
[58] Philosoph. Trans., 1773, p. 262.