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The Descent of Man

The Descent of Man

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extent, understand how it is that with closely<br />

allied species the sexes either differ to an astonishing<br />

degree, or are identical in colour. As all<br />

the successive steps in the process <strong>of</strong> variation<br />

are necessarily transmitted through the female,<br />

a greater or less number <strong>of</strong> such steps might<br />

readily become developed in her; and thus we<br />

can understand the frequent gradations from<br />

an extreme difference to none at all between the<br />

sexes <strong>of</strong> allied species. <strong>The</strong>se cases <strong>of</strong> gradation,<br />

it may be added, are much too common to favour<br />

the supposition that we here see females<br />

actually undergoing the process <strong>of</strong> transition<br />

and losing their brightness for the sake <strong>of</strong> protection;<br />

for we have every reason to conclude<br />

that at any one time the greater number <strong>of</strong> species<br />

are in a fixed condition.<br />

MIMICRY.<br />

This principle was first made clear in an admirable<br />

paper by Mr. Bates (29. 'Transact. Linn.

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