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key.” And the argument requires that the same should be
said of all the four classes of phenomena which he cites.
After all that has been said in the previous sections of
this work, it is unnecessary here to consider every instance
which has been brought forward by Mr. Spencer. At the
same time it may be well to select a few as illustrations
of the different steps of his argument.
Among the instances adduced to prove that Natural
Selection must have produced certain results, because the
inherited effects of use and disuse will not account for
them, we find the case of the thorns of the bramble cited.
Now, with respect to the origin of thorns, the experience
of desert plants may be cited, and it will then be seen
that thorns are the result of the direct action of the dry
and arid air of the desert.
Mr. Spencer further says :—
“ Plants which are rendered uneatable by the thick woolly coatings
of their leaves, cannot have had these coatings produced by any
process of reaction against the action of enemies ; for there is no
imaginable reason why, if one part of a plant is eaten, the rest
should thereafter begin to develope the hairs on its surface.”—(p. j.)
But if we consider that the leaves of plants are directly
influenced by the conditions of life to which they are
subjected, an imaginable reason is at once found without
being compelled to call in the action of Natural Selection.
Again Mr. Spencer asks :—
“ Or how can those seeds which contain essential oils, rendering
them unpalatable to birds, have been made to secrete such essential
oils by these actions of birds which they restrain ?”—(/. j.)
But the reply at once suggests itself, that the production of
essential oils is the result of the action of certain con
ditions of life, and so the necessity for the introduction of
Natural Selection is again removed.