28.]
[Footnote 56: _Amaryllidaceae_, by the Hon. and Rev. William Herbert, p.
379.]
[Footnote 57: _Origin of Species_, p. 239.]
[Footnote 58: _Origin of Species_, sixth edition, p. 9.]
[Footnote 59: In the _Medico-Chirurgical Transactions_, vol. liii.
(1870), Dr. Ogle has adduced some curious physiological facts bearing on
the presence or absence of white colours in the higher animals. He
states that a dark pigment in the olfactory region of the nostrils is
essential to perfect smell, and that this pigment is rarely deficient
except when the whole animal is pure white, and the creature is then
almost without smell or taste. He observes that there is no proof that,
in any of the cases given above, the black animals actually eat the
poisonous root or plant; and that the facts are readily understood if
the senses of smell and taste are dependent on a pigment which is absent
in the white animals, who therefore eat what those gifted with normal
senses avoid. This explanation however hardly seems to cover the facts.
We cannot suppose that almost all the sheep in the world (which are
mostly white) are without smell or taste.
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