It is because these facts of variation are so important and so little
understood, that they have been discussed in what will seem to some
readers wearisome and unnecessary detail. Many naturalists, however,
will hold that even more evidence is required; and more, to almost any
amount, could easily have been given. The character and variety of that
already adduced will, however, I trust, convince most readers that the
facts are as stated; while they have been drawn from a sufficiently wide
area to indicate a general principle throughout nature.
If, now, we fully realise these facts of variation, along with those of
rapid multiplication and the struggle for existence, most of the
difficulties in the way of comprehending how species have originated
through natural selection will disappear. For whenever, through changes
of climate, or of altitude, or of the nature of the soil, or of the area
of the country, any species are exposed to new dangers, and have to
maintain themselves and provide for the safety of their offspring under
new and more arduous conditions, then, in the variability of all parts,
organs, and structures, no less than of habits and intelligence, we have
the means of producing modifications which will certainly bring the
species into harmony with its new conditions.
Pages:
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234