ature our
cabbages, lettuces, and other culinary vegetables, in the state in which
they appear in our gardens? Is it not the same in regard to a great
quantity of animals which domesticity has changed or considerably
modified?"[793] Our domestic fowls and pigeons are unlike any wild
birds. Our domestic ducks and geese have lost the faculty of raising
themselves into the higher regions of the air, and crossing extensive
countries in their flight, like the wild ducks and wild geese from which
they were originally derived. A bird which we breed in a cage cannot,
when restored to liberty, fly like others of the same species which have
been always free. This small alteration of circumstances, however, has
only diminished the power of flight, without modifying the form of any
part of the wings. But when individuals of the same race are retained in
captivity during a considerable length of time, the form even of their
parts is gradually made to differ, especially if climate, nourishment,
and other circumstances be also altered.

The numerous races of dogs which we have produced by domesticity are
nowhere to be found in a wild state. In nature we should seek in vain
for mastiffs, harriers, spaniels, greyhounds, and other races, between
which the differences are sometimes so great that they would be readily
admitted as specific between wild animals; "yet all these have sprung
originally from a single race, at first approaching very near to a wolf,
if, indeed, the wolf be not the true type which at some period or other
was domesticated by man."

Although important changes in the nature of the places which they
inhabit modify the organization of animals as well as vegetables; yet
the former, says Lamarck, require more time to complete a considerable
degree of transmutation; and, consequently, we are less sensible of such
occurrences. Next to a diversity of the medium in which animals or
plants may live, the circumstances which have most influence in
modifying their organs are differences in exposure, climate, the nature
of the soil, and other local particulars. These circumstances are as
varied as are the characters of the species, and, like them, pass by
insensible shades into each other, there being every intermediate
gradation between the opposite extremes. But each locality remains for a
very long time the same, and is altered so slowly that we can only
become conscious of the reality of the change by consulting geological
m