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 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 imaginal 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