The Descent of Man

etc., is utterly inexplicable. (56. Prof. Bianconi,
in a recently published work, illustrated by
admirable engravings ('La Theorie Darwinienne
et la creation dite independante,'
1874), endeavours to shew that homological
structures, in the above and other cases, can be
fully explained on mechanical principles, in
accordance with their uses. No one has shewn
so well, how admirably such structures are
adapted for their final purpose; and this adaptation
can, as I believe, be explained through
natural selection. In considering the wing of a
bat, he brings forward (p. 218) what appears to
me (to use Auguste Comte's words) a mere
metaphysical principle, namely, the preservation
"in its integrity of the mammalian nature of
the animal." In only a few cases does he discuss
rudiments, and then only those parts which are
partially rudimentary, such as the little hoofs of
the pig and ox, which do not touch the ground;
these he shews clearly to be of service to the
animal. It is unfortunate that he did not con-