le the male to grasp its consort and also
perhaps to cling to the feathers, and thus give it a superiority over
the weaker sex in its advances towards courtship. Why is this advantage
possessed by the males of this genus alone? The world of insects, and of
animals generally abounds in such instances, though existing in other
organs, and the developmentist dimly perceives in such departures from a
normal type of structure, the origin of new generic forms, whether due
at first to a seemingly accidental variation, or, as in this instance,
perhaps, to long use as prehensile organs through successive generations
of lice having the antennae slightly diverging from the typical
condition, until the present form has been developed. Another generation
of naturalists will perhaps unanimously agree that the Creator has thus
worked through secondary laws, which many of the naturalists of the
present day are endeavoring, in a truly scientific and honest spirit of
inquiry, to discover.

[Illustration: 124. Louse of the Goat.]

[Illustration: 123. Louse of the Cat.]

In their claw or leg-like form these male antennae also repeat in the
head, the general form of the legs, whose prehensile and grasping
functions they assume. We have seen above that the appendages of the
head and thorax are alike in the embryo, and the present case is an
interesting example of the unity of type of the jointed appendages of
insects, and articulates generally.

[Illustration: 120. Antennae of Goniodes.]

Another point of interest in these degraded insects is, that the process
of degradation begins either late in the life of the embryo or during
the changes from the larval to the adult, or winged state. An instance
of the latter may be observed in the wingless female of the canker worm,
so different from the winged male; this difference is created after the
larval stage, for the caterpillars of both sexes are the same, so far as
we know. So with numerous other examples among the moths. In the louse,
the embryo, late in its life, resembles the embryos of other insects,
even Corixa, a member of a not remotely allied family. But just before
hatching the insect assumes its degraded louse physiognomy. The
developmentist would say that this process of degradation points to
causes acting upon the insect just before or immediately after birth,
inducing the retrogression and retardation of development, and would
consider it as an argument for the evolution of sp