e country, it will seize on the place of that
inhabitant, however different that may be from its own place. Hence it
will cause him no surprise that there should be geese and frigate-birds
with webbed feet, living on the dry land and rarely alighting on the
water, that there should be long-toed corncrakes, living in meadows
instead of in swamps; that there should be woodpeckers where hardly a
tree grows; that there should be diving thrushes and diving Hymenoptera,
and petrels with the habits of auks.

ORGANS OF EXTREME PERFECTION AND COMPLICATION.

To suppose that the eye with all its inimitable contrivances for
adjusting the focus to different distances, for admitting different
amounts of light, and for the correction of spherical and chromatic
aberration, could have been formed by natural selection, seems, I freely
confess, absurd in the highest degree. When it was first said that the
sun stood still and the world turned round, the common sense of mankind
declared the doctrine false; but the old saying of Vox populi, vox Dei,
as every philosopher knows, cannot be trusted in science. Reason tells
me, that if numerous gradations from a simple and imperfect eye to one
complex and perfect can be shown to exist, each grade being useful to
its possessor, as is certainly the case; if further, the eye ever varies
and the variations be inherited, as is likewise certainly the case;
and if such variations should be useful to any animal under changing
conditions of life, then the difficulty of believing that a perfect and
complex eye could be formed by natural selection, though insuperable by
our imagination, should not be considered as subversive of the theory.
How a nerve comes to be sensitive to light, hardly concerns us more than
how life itself originated; but I may remark that, as some of the lowest
organisms in which nerves cannot be detected, are capable of perceiving
light, it does not seem impossible that certain sensitive elements
in their sarcode should become aggregated and developed into nerves,
endowed with this special sensibility.

In searching for the gradations through which an organ in any species
has been perfected, we ought to look exclusively to its lineal
progenitors; but this is scarcely ever possible, and we are forced
to look to other species and genera of the same group, that is to the
collateral descendants from the same parent-form, in order to see what
gradations are possible, and for the chance o