stronger case, for these have been exposed to great changes of climate and
have migrated over great distances; whereas, in Egypt, during the last
several thousand years, the conditions of life, as far as we know, have
remained absolutely uniform. The fact of little or no modification having
been effected since the glacial period, would have been of some avail
against those who believe in an innate and necessary law of development,
but is powerless against the doctrine of natural selection or the survival
of the fittest, which implies that when variations or individual
differences of a beneficial nature happen to arise, these will be
preserved; but this will be effected only under certain favourable
circumstances.

The celebrated palaeontologist, Bronn, at the close of his German
translation of this work, asks how, on the principle of natural selection,
can a variety live side by side with the parent species? If both have
become fitted for slightly different habits of life or conditions, they
might live together; and if we lay on one side polymorphic species, in
which the variability seems to be of a peculiar nature, and all mere
temporary variations, such as size, albinism, etc., the more permanent
varieties are generally found, as far as I can discover, inhabiting
distinct stations, such as high land or low land, dry or moist districts.
Moreover, in the case of animals which wander much about and cross freely,
their varieties seem to be generally confined to distinct regions.

Bronn also insists that distinct species never differ from each other in
single characters, but in many parts; and he asks, how it always comes that
many parts of the organisation should have been modified at the same time
through variation and natural selection? But there is no necessity for
supposing that all the parts of any being have been simultaneously
modified. The most striking modifications, excellently adapted for some