nto worker-ids,
we shall see that the germ-plasm of the sexual ants must contain three
kinds of ids, male, female, and worker ids, or if the workers have
diverged into soldiers and nest-builders, then four kinds. We
understand that the worker-ids arose because their determinants struck
out a useful path of variation, whether upward or downward, and that
they continued in this path until the highest attainable degree of
utility of the parts determined was reached. But in addition to the
organs of positive or negative selection-value, there were some which
were indifferent as far as the success and especially the functional
capacity of the workers was concerned: wings, ovarian tubes,
_receptaculum seminis_, a number of the facets of the eye, perhaps
even the whole eye. As to the ovarian tubes it is is possible that
their degeneration was an advantage for the workers, in saving energy,
and if so selection would favour the degeneration; but how could the
presence of eyes diminish the usefulness of the workers to the colony?
or the minute _receptaculum seminis_, or even the wings? These parts
have therefore degenerated _because they were of no further value to
the insect_. But if selection did not influence the setting aside of
these parts because they were neither of advantage nor of disadvantage
to the species, then the Darwinian factor of selection is here
confronted with a puzzle which it cannot solve alone, but which at
once becomes clear when germinal selection is added. For the
determinants of organs that have no further value for the organism,
must, as we have already explained, embark on a gradual course of
retrograde development.

In ants the degeneration has gone so far that there are no
wing-rudiments present in _any_ species, as is the case with so many
butterflies, flies, and locusts, but in the larvae the imaginable
discs of the wings are still laid down. With regard to the ovaries,
degeneration has reached different levels in different species of
ants, as has been shown by the researches of my former pupil,
Elizabeth Bickford. In many species there are twelve ovarian tubes,
and they decrease from that number to one; indeed, in one species no
ovarian tube at all is present. So much at least is certain from what
has been said, that in this case _everything_ depends on the
fluctuations of the elements of the germ-plasm. Germinal selection,
here as elsewhere, presents the variations of the determinants, and
per