very great slowness of the
changes which have gone on. A little attention given to the facts
which I am about to cite will afford the strongest proof of my
assertion.

"What nature does after a great length of time we do every day by
suddenly changing, as regards a living being, the circumstances in
which it and all the individuals of its species are placed.

"All botanists know that the plants which they transplant from their
natal spot into gardens for cultivation there gradually undergo
changes which in the end render them unrecognizable. Many plants
naturally very hairy, there become glabrous or nearly so; a quantity
of those which were procumbent or trailing there have erect stems;
others lose their spines or their thorns; finally, the dimensions of
parts undergo changes which the circumstances of their new situation
infallibly produce. This is so well known that botanists prefer not
to describe them, at least unless they are newly cultivated. Is not
wheat (_Triticum sativum_) a plant brought by man to the state
wherein we actually see it, which otherwise I could not believe? Who
can now say in what place its like lives in nature?

"To these known facts I will add others still more remarkable, and
which confirm the view that change of circumstances operates to
change the parts of living organisms.

"When _Ranunculus aquatilis_ lives in deep water, all it can do
while growing is to make the end of its stalks reach the surface of
the water where they flourish. Then all the leaves of the plant are
finely cut or pinked.[168] If the same plant grows in shallower
water the growth of its stalks may give them sufficient extent for
the upper leaves to develop out of the water; then its lower leaves
only will be divided into hair-like joints, while the upper ones
will be simple, rounded, and a little lobed.[169] This is not all:
when the seeds of the same plant fall into some ditch where there is
only water or moisture sufficient to make them germinate, the plant
develops all its leaves in the air, and then none of them is divided
into capillary points, which gives rise to _Ranunculus hederaceus_,
which botanists regard as a species.

"Another very striking proof of the effect of a change of
circumstances on a plant submitted to it is the following:

"It is observed that when a tuft of _Juncus bufonius_ grows very
near the edge of the water in