organs, though fitted in the adult members for purposes as different as
possible. Larv are active embryos, which have become specially
modified in relation to their habits of life, through the principle of
modifications being inherited at corresponding ages. On this same
principle and bearing in mind, that when organs are reduced in size,
either from disuse or 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 principle of inheritance the occurrence of
rudimentary organs and their final abortion, present to us no
inexplicable difficulties; on the contrary, their presence might have
been even anticipated. The importance of embryological characters and
of rudimentary organs in classification is intelligible, on the view
that an arrangement is only so far natural as it is 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 of organic beings, with which this world
is
peopled, have 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 XIV.
RECAPITULATION AND CONCLUSION.
Recapitulation of the difficulties on 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.
342