m VARIABILITY OF SPECIES IN A STATE OF NATURE 65 
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, inde¬ 
pendently, the materials constantly ready for natural selection 
CARDINAUS l/IRGINIANUS. 58 specimens. Florida. 
Tail. 
Length 
9 
• • 
• • 
• •• 
•••••••••• 
Wing. 
>e n 
Bird. 
99 
999 
9090 
00009 99 
99909999 099 
99900999 ••• 
• • 
• •• 
• •• • 
• ••• • 
..... 
i’s Birdi 
(From Allen's Birds of Florida, p.281) 
Fio. 12 
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 pro¬ 
ducing new species, genera, and higher groups. 
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 
F 
