moments that are allotted me, to a purely scientific subject.

At those dinner-tables referred to, I have often been asked, as many of
you have been, if I could tell how it happened, that when a pine wood was
cut down an oak one commonly sprang up, and _vice versa_. To which I have
answered, and now answer, that I can tell,--that it is no mystery to me.
As I am not aware that this has been clearly shown by any one, I shall lay
the more stress on this point. Let me lead you back into your wood-lots
again.

When, hereabouts, a single forest tree or a forest springs up naturally
where none of its kind grew before, I do not hesitate to say, though in
some quarters still it may sound paradoxical, that it came from a seed. Of
the various ways by which trees are _known_ to be propagated,--by
transplanting, cuttings, and the like,--this is the only supposable one
under these circumstances. No such tree has ever been known to spring from
anything else. If any one asserts that it sprang from something else, or
from nothing, the burden of proof lies with him.

It remains, then, only to show how the seed is transported from where it
grows, to where it is planted. This is done chiefly by the agency of the
wind, water, and animals. The lighter seeds, as those of pines and maples,
are transported chiefly by wind and water; the heavier, as acorns and
nuts, by animals.

In all the pines, a very thin membrane, in appearance much like an
insect's wing, grows over and around the seed, and independent of it,
while the latter is being developed within its base. Indeed this is often
perfectly developed, though the seed is abortive; nature being, you would
say, more sure to provide the means of transporting the seed, than to