reeping and trailing, then become erect; others lose their
spines or their prickles; others still, from the woody and perennial
condition which their stem possesses in a warm climate, pass, in our
climate, into an herbaceous condition, and among these several are
nothing more than annual plants; finally, the dimensions of their
parts themselves undergo very considerable changes. These effects of
changes of circumstances are so well known that botanists prefer not
to describe garden plants, at least only those which have been newly
cultivated.

"Is not cultivated wheat (_Triticum sativum_) only a plant brought
by man into the condition in which we actually see it? Who can tell
me in what country such a plant lives in a state of nature--that is
to say, without being there the result of its culture in some
neighboring region?

"Where occur in nature our cabbage, lettuce, etc., in the condition
in which we see them in our kitchen-gardens? Is it not the same as
regards a number of animals which domestication has changed or
considerably modified?

"What very different races among our fowls and domestic pigeons,
which we have obtained by raising them in different circumstances
and in different countries, and how vainly do we now endeavor to
rediscover them in nature!

"Those which are the least changed, without doubt by a more recent
process of domestication, and because they do not live in a climate
which is foreign to them, do not the less possess, in the condition
of some of their parts, great differences produced by the habits
which we have made them contract. Thus our ducks and our domestic
geese trace back their type to the wild ducks and geese; but ours
have lost the power of rising into the high regions of the air, and
of flying over extensive regions; finally, a decided change has
been wrought in the state of their parts compared with that of
animals of the race from which they have descended.

"Who does not know that such a native bird, which we raise in a cage
and which lives there five or six years in succession, and after
that replaced in nature--namely, set free--is then unable to fly
like its fellows which have always been free? The slight change of
circumstance operating on this individual has only diminished its
power of flight, and doubtless has not produced any change in the
shape of its parts. But if a numerous series of gener