second
sex."

Now, if we examine the simplest types of the sexes in the lower
reaches of the animal kingdom,[18] below the vertebrates we find the
same conditions prevailing. The male is frequently inconspicuous in
size, of use only to fertilise the female, and in some cases incapable
of any other function; the female, on the other hand, remains
unchanged and carries on the life of the species. So marked is this
difference among some species that the male must be regarded as a
fallen representative of the female, having not only greatly
diminished in size, but undergone thorough degeneration in
structure.[19] In certain extreme cases what have been well called
"pigmy males" illustrate this contrast in an almost ridiculous degree.
This is well seen among the common rotifers, where the males are much
smaller than the females and very degenerate. Sometimes they seem to
have dwindled out of existence altogether, as only females are to be
seen; in other cases, though present they fail even to accomplish
their proper function of fertilisation, and as reproduction is carried
on by the females, they are not only minute but useless. Nor are such
cases of male degeneration confined to this group. The whole family of
the _Abdominalia_ (cirripedes) have the sexes separate; and the males,
comparatively very small, are attached to the body of each female, and
are entirely passive and dependent upon her.[20] Some of these male
parasites are so far degenerated as to have lost their digestive
organs and are incapable of any function except fertilisation: the
male _Sygami_ (menatodes), for instance, being so far effaced that it
is nothing but a testicle living on the female.[21] A yet more
striking instance is furnished by the curious green worm _Bonellia_,
where the male appears like a remote ancestor of the female, on whom
it lives parasitically. Somewhat similar is the cocus insect, among
whom the males are very degenerate, small, blind and wingless.

This phenomenon of minute parasitic male fertilisers in connection
with normally developed females was noticed by Darwin, and his
observations have been confirmed by Van Beneden, by Huxley, Haeckel,
Milne Edwards, Fabre, Patrick Geddes, and many other eminent
entomologists.[22] A full study of these early forms of sexuality
should be made by all who wish to understand the problem of woman;
their life-histories furnish prophecies of many large facts. I wish it
were possible for me to b