often insisted
on by the illustrious Cuvier, is fully embraced by the principle of
natural selection. For natural selection acts by either now adapting the
varying parts of each being to its organic and inorganic conditions
of life; or by having adapted them during past periods of time: the
adaptations being aided in many cases by the increased use or disuse
of parts, being affected by the direct action of external conditions
of life, and subjected in all cases to the several laws of growth and
variation. Hence, in fact, the law of the Conditions of Existence is the
higher law; as it includes, through the inheritance of former variations
and adaptations, that of Unity of Type.

CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION.

Longevity--Modifications not necessarily simultaneous--Modifications
apparently of no direct service--Progressive development--Characters of
small functional importance, the most constant--Supposed incompetence
of natural selection to account for the incipient stages of useful
structures--Causes which interfere with the acquisition through natural
selection of useful structures--Gradations of structure with changed
functions--Widely different organs in members of the same class,
developed from one and the same source--Reasons for disbelieving in
great and abrupt modifications.

I will devote this chapter to the consideration of various miscellaneous
objections which have been advanced against my views, as some of the
previous discussions may thus be made clearer; but it would be useless
to discuss all of them, as many have been made by writers who have not
taken the trouble to understand the subject. Thus a distinguished German
naturalist has asserted that the weakest part of my theory is, that I
consider all organic beings as imperfect: what I have really said is,
that all are not as perfect as they might have been in relation to their
conditions; and this is shown to be the case by so many native forms
in many quarters of the world having yielded their places to intruding
foreigners. Nor can organic beings, even if they were at any one time
perfectly adapted to their conditions of life, have remained so, when
their conditions changed, unless they themselves likewise changed; and
no one will dispute that the physical conditions of each country, as
well as the number and kinds of its inhabitants, have undergone many
mutations.

A critic has lately ins