ccessive slight variations, not necessarily
or generally supervening at a very early period of life, and being
inherited at a corresponding period, we can understand the leading facts
in embryology; namely, the close resemblance in the individual embryo
of the parts which are homologous, and which when matured become
widely different in structure and function; and the resemblance of the
homologous parts or organs in allied though distinct species, though
fitted in the adult state for habits as different as is possible. Larvae
are active embryos, which have become specially modified in a greater
or less degree in relation to their habits of life, with their
modifications inherited at a corresponding early age. On these same
principles, and bearing in mind that when organs are reduced in size,
either from disuse or through natural selection, it will generally be at
that period of life when the being has to provide for its own wants, and
bearing in mind how strong is the force of inheritance--the occurrence
of rudimentary organs might even have been anticipated. The importance
of embryological characters and of rudimentary organs in classification
is intelligible, on the view that a natural arrangement must be
genealogical.

Finally, the several classes of facts which have been considered in
this chapter, seem to me to proclaim so plainly, that the innumerable
species, genera and families, with which this world is peopled, are all
descended, each within its own class or group, from common parents, and
have all been modified in the course of descent, that I should without
hesitation adopt this view, even if it were unsupported by other facts
or arguments.

CHAPTER XV. RECAPITULATION AND CONCLUSION.

Recapitulation of the objections to the theory of Natural
Selection--Recapitulation of the general and special circumstances
in its favour--Causes of the general belief in the immutability
of species--How far the theory of Natural Selection may be
extended--Effects of its adoption on the study of Natural
History--Concluding remarks.

As this whole volume is one long argument, it may be convenient to the
reader to have the leading facts and inferences briefly recapitulated.

That many and serious objections may be advanced against the theory of
descent with modification through variation and natural selection, I do
not deny. I have endeavoured to give to them their full force. Nothing
at first can appear more