11. The great divergence of
the dots, when even a few specimens are compared, shows that the curve,
with high numbers, would be a flat one like the lower curve in the
illustration here given. This being the case it would follow that a very
large proportion of the total number of individuals constituting a
species would diverge considerably from its average condition as regards
each part or organ; and as we know from the previous diagrams of
variation (Figs. 1 to 7) that each part varies to a considerable extent,
_independently_, the materials constantly ready for natural selection to
act upon are abundant in quantity and very varied in kind. Almost any
combination of variations of distinct parts will be available, where
required; and this, as we shall see further on, obviates one of the most
weighty objections which have been urged against the efficiency of
natural selection in producing new species, genera, and higher groups.
[Illustration: FIG. 12.]
_Variation in the Mammalia._
Owing to the generally large size of this class of animals, and the
comparatively small number of naturalists who study them, large series
of specimens are only occasionally examined and compared, and thus the
materials for determining the question of their variability in a state
of nature are comparatively scanty.
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