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1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1872

from ordinary single varieties only 1869
only 1866
OMIT 1872

the two forms. 1869
OMIT 1872
two forms, from ordinary single varieties. 1866

the fertile plants 1869
these single and fertile plants 1866
These latter, by which alone the variety can be propagated, 1872

producing single flowers may 1869
may 1866 1872

of an ant-community, 1866 1869
ants, 1872

sterile double-flowered plants, which are regularly produced in large numbers, 1866 1869
double sterile plants 1872

1 blocks not present in 1859 1860 1861 1866 1869; present in 1872
As with the varieties of the stock, so with social insects, selection has been applied to the family, and not to the individual, for the sake of gaining a serviceable end.

Thus I believe it has been with social insects: a 1859 1860 1861 1866 1869
Hence we may conclude that 1872

has been advantageous to the community: 1859 1860 1861 1866 1869
have proved advantageous: 1872

of the same community 1859 1860 1861 1866 1869
have 1872

And I believe that 1859 1860 1861 1866 1869
OMIT 1872

until 1859 1860 1861 1866 1869
many times, until 1872

plants.
plants,
which
which
differ
differ
from ordinary single varieties only
in
in
their
their
power
power
of
of
producing
producing
the two forms.
Thus
Thus
the fertile plants producing single flowers may be compared with the
fertile male
males
and
female
females
of an ant-community, and the sterile double-flowered plants, which are regularly produced in large numbers, with the
many sterile
many sterile
neuters of the same community. Thus I believe it has been with social insects: a slight
modifications
modification
of
structure
structure,
or
instinct,
of instinct,
correlated with the sterile condition of certain members of the community, has been advantageous to the community: consequently the fertile males and females of the same community flourished, and transmitted to their fertile offspring a tendency to produce sterile members
with
having
the same
modifications.
modification.
And I believe that
This
this
process
must have
has
been
repeated
repeated,
until that prodigious amount of difference between the fertile and sterile females of the same species has been produced, which we see in
many
so many
social insects.
But we have not as yet touched on the climax of the difficulty; namely, the fact that the neuters of several ants differ, not only from the fertile females and males, but from each other, sometimes to an almost incredible degree, and are thus divided into two or even three castes. The castes, moreover, do not
commonly
generally
graduate into each other, but are perfectly well defined; being as distinct from each
other,
other
as are any two species of the same genus, or rather as any two genera of the same family. Thus in Eciton, there are working and soldier neuters, with jaws and instincts extraordinarily different: in Cryptocerus, the workers of one caste alone carry a wonderful sort of shield on their heads, the use of which is quite unknown: in the Mexican
Myrme- cocystus,
Myrmecocystus,
the workers of one caste never leave the nest; they are fed by the workers of another caste, and they have an enormously developed abdomen which