r nature to
have created for the parts of animals as many forms as the diversity
of circumstances in which they have to live had required, and that
these forms and also the circumstances had never varied.

"This is certainly not the existing order of things, and if it were
really such, we should not have the race-horses of England; we
should not have our great draft horses, so clumsy and so different
from the first named, for nature herself has not produced their
like; we should not, for the same reason, have terrier dogs with bow
legs, greyhounds so swift in running, water-spaniels, etc.; we
should not have tailless fowls, fantail pigeons, etc.; finally, we
could cultivate the wild plants as much as we pleased in the rich
and fertile soil of our gardens without fearing to see them change
by long culture.

"For a long time we have felt the force of the saying which has
passed into the well-known proverb--_habits form a second nature_.

"Assuredly, if the habits and nature of each animal can never vary,
the proverb is false, has no foundation, and does not apply to the
instances which led to its being spoken.

"If we should seriously consider all that I have just stated, it
might be thought that I had good reason when in my work entitled
_Recherches sur les Corps vivans_ (p. 50) I established the
following proposition:

"'It is not the organs--that is to say, the nature and form of the
parts of the body of an animal--which have given rise to its habits
and its special faculties; but it is, on the contrary, its habits,
its manner of life, and the circumstances in which are placed the
individuals from which it originates, which have, with time, brought
about the form of its body, the number and condition of its organs,
finally, the faculties which it enjoys.'

"If we weigh this proposition, and if we recall all the observations
which nature and the state of things continually lead us to do, then
its importance and its solidity will become more evident.

"Time and favorable circumstances are, as I have already said, the
two principal means which nature employs to give existence to all
her productions: we know that time for her has no limits, and that
consequently it is ever at her disposal.

"As to the circumstances of which she has need, and which she uses
still daily to cause variations in all that she continues to
produce, we can say