198 Mr. B. T. Lowne on 
low development of their nervous system, although I 
should unhesitatingly apply it to the higher Hymenop- 
tera and Diptera. I see, however, that Mr. Darwin has 
in his last work * applied the principle to account for the 
production of these horns. 
This long digression leads me to the wings of insects, 
which are really quite analogous to the cutaneous knobs 
and horns, so far as their relation to the nourishment 
of the body is concerned. The absence of wings in 
the female is well known to be excessively frequent, 
and there is no more remarkable instance, showing their 
relation to the female sexual organs, than the phenomena 
observed in Aphis. 
The agamic Aphides, which have excessively imperfect 
female sexual organs, without either sperm sacs or colla- 
teral t (shell-secreting?) glands, frequently have wings, 
whilst these never occur in those sexually perfect. 
From all the above facts, I think it probable, that the 
apterous condition of female insects is an acquired one, 
dependent on the amount of nourishment received by the 
larva. I also think it highly improbable that the wings 
could have been developed by natural selection in one sex 
alone, without having been inherited by the other sex, 
in some few insects. And I think it more probable, that 
altered conditions of larval life, have gradually led to 
suppression of the wings in one sex, and that the winged 
forms are reversions to an anterior type. 
Third. The early appearance of the sexual organs, 
their peculiar mode of development, and their occasional 
premature development, may now be considered. 
* «Descent of Man.’ 
+ Closely related to this question, is the wider one of coloration in 
insects, and, as Mr. Darwin has suggested to me, the greater variability of 
the males than of the females. I have already noticed elsewhere, that 
the oxidization of the fat bodies of the larva of the blow-fly, produces the 
pigment with which the integument is coloured. The fat bodies also 
produce the material from which the sexual elements, as well as most of 
the tissues are nourished, hence the male element being much less than 
the female, more material remains for the development of colour and of 
the other organs. As the best fed forms are usually more variable, and 
as the amount of pigment is closely correlated with the conditions of the 
fat bodies of the larva, I think it probable that both coloration and vari- 
ability may be directly influenced by sex, in the manner above indicated. 
t I believe these glands in the fly, secrete the very hard, opaque egg- 
shell which surrounds the eggs when they are laid. 
