case of the Giant Stag. Darwin himself gave a pretty illustration to show
how imposing the difference between the two kinds of workers in one species
would seem if we translated it into human terms. In regard to the Driver
ants (Anomma) we must picture to ourselves a piece of work, "for instance
the building of a house, being carried on by two kinds of workers, of which
one group was five feet four inches high, the other sixteen feet high."
("Origin of Species" (6th edition), page 232.)

Although the ant is a small animal as compared with man or with the Irish
Elk, the "soldier" with its relatively enormous jaws is hardly less heavily
burdened than the Elk with its antlers, and in the ant's case, too, a
strengthening of the skeleton, of the muscles, the nerves of the head, and
of the legs must have taken place parallel with the enlargement of the
jaws. HARMONIOUS ADAPTATION (coadaptation) has here been active in a high
degree, and yet these "soldiers" are sterile! There thus remains nothing
for it but to refer all their adaptations, positive and negative alike, to
processes of selection which have taken place in the rudiments of the
workers within the egg and sperm-cells of their parents. There is no way
out of the difficulty except the one Darwin pointed out. He himself did
not find the solution of the riddle at once. At first he believed that the
case of the workers among social insects presented "the most serious
special difficulty" in the way of his theory of natural selection; and it
was only after it had become clear to him, that it was not the sterile
insects themselves but their parents that were selected, according as they
produced more or less well adapted workers, that he was able to refer to
this very case of the conditions among ants "IN ORDER TO SHOW THE POWER OF
NATURAL SELECTION" ("Origin of Species", page 233; see also edition 1, page
242.). He explains his view by a simple but interesting illustration.
Gardeners have produced, by means of long continued artificial selection, a
variety of Stock, which bears entirely double, and therefore infertile