development of man, where naturally the difficulty occurs with its
greatest force.

(1) I come at once to the great difficulty that, if all existing forms
are due to the occurrence of changes that helped the creature in the
struggle for existence, how is it possible now to account for forms
which are not advantageous? yet such forms are numerous. Of this
objection, the existence of imperfect or neuter bees and ants is an
instance. The modification in form which these creatures exhibit is of
no advantage to them. It _is_ a great advantage, no doubt, to the other
bees; but then this introduces a view of some power _making_ one thing
for the benefit of another, not a change in the form itself adapted of
course to its _own_ advantage--since natural laws, forces, and
conditions of environment could not conceivably _design_ the advantage
of another form, and cause one to change for the benefit of that other.

Why is it, again, that crabs and crayfish can only grow by casting off
their shells, during which process they often die, as well as remain
exposed defenceless to the attacks of enemies? Why should stags shed
their horns also, leaving them defenceless for a time? Other animals do
not do so, and there is nothing in the nature of the horn which requires
it.

This brief allusion is here sufficient. Mr. Mivart's work gives it at
large.

(2) Passing next to the question of the advantage of _incomplete
stages_--portions of a mechanism only useful when complete, the most
striking examples may be found in the Vegetable kingdom. The
fertilization of flowering plants is effected by the pollen, a yellow