98 CERTAIN PARASITIC INSECTS. 
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 "sport" or accidental varia- 
tion, or, as in this instance perhaps, to long use as prehensile 
organs through successive generations of lice having the 
antenne slightly diverging from the typical condition, until 
the present form has been developed. Another generation 
of naturalists will perhaps unanimously agree that the Cre- 
ator 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. 
In their claw or leg-like form these male antenne also 
repeat in the head, the general form of the legs, whose pre- 
hensile 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. 
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 dif- 
ferent from the winged volant 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 ex- 
amples 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 degrada- 
tion 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 specific forms by causes act- 
ing on the animal while battling with its fellows in the 
