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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.