completely: the same ground bringing forth
every succeeding year new individuals of this
detested species, although their predecessors
had invariably been pulled up and burnt. I
have now learned the cause of what appeared
unaccountable to us then. It must have been
the presence of latent seeds coming to light
from time to time, as I know that these seeds,
when consigned to the earth, may remain there
during two, three, and even ten or twenty
years without losing their power of
germination."

A plant which had not been seen for forty
years in the Botanical Garden of Upsal,
reappeared there spontaneously in the year 1731
after the ground had been dug up. Another
plant, a lobelia, reappeared and flourished in
the Botanical Garden of Amsterdam, after lying
buried in the earth twenty years. Cucumber
seeds have been kept forty years, and even fifty
years, without losing their germinative power.
The railway excavations every where have brought
to light, plants long supposed to be extinct.

Corn found in the ruins after the fire of
London has been raised; wheat which has been
enclosed in the wrappings of an Egyptian
mummy has been reared, and has reproduced
fruit in Germany; Indian corn taken from the
tombs of the Incas has done the same thing
in America. It has been observed that when
the virgin forests of America have been burnt
down, and the land ploughed up, an entirely
new flora has appeared: a fact which has been
accounted for, by the supposition that the seeds
had been buried forages, in depths beyond the
reach of vegetation.

The ground or earth nut (Arachis) is the
fruit of a plant growing in South America, not
unlike our bean. After the flowers fall off, the
young pods bend until they reach the ground,
where they bury their seeds three or four inches
under the soil. These nuts contain an extremely
sweet fixed oil, like that of almonds, which, if
they were allowed to ripen above ground, would
become rancid and useless, and the seeds would
not germinate when planted. The negroes of
South Carolina make these earth nuts their
principal food.

The seeds of the pine and fir trees are
protected in a somewhat similar manner. On
account of their oily nature, too much heat
would be apt to make them rancid and sterile;
therefore the scales of the cone, which, while the
tree is in flower are spread out when the seed is
ripe, close one over the other like the tiles of a
roof, effectually shutting out the rain; and in
proportion as winter approaches and the cold
increases, the scales tighten more and more
round the seeds they defend. About the
beginning of April, when the returning sun
sends forth his first warm rays, the scales of the
cone open, and let the seeds fall to be received
into the bosom of the tepid earth, where vernal
showers soon draw out their roots.

The subterraneous pea (Lathyrus subterraneum)
bears very few blossoms upon its
flower-stalk, and still fewer fruits; but there
spring from the plant, white flower-stalks,
having no leaves, and bearing not variegated
coloured flowers like the others, but white
ones. These white flowers produce fruit which
is immediately consigned to the earth, and thus
screened from devastation by birds. It would
appear that the coloured flowers are for show,
and the white flowers for use. The seeds of one
of the clovers are protected in the same way.

Certain seeds, owing to a curious arrangement
of their various parts, have a tendency to move
about. If a seed of the plant called crupina (a
kind of centaury) is placed in the palm of the
hand, it will be sure to move off; and if put
between the stocking and the back part of the
foot, it will work its way over the whole body,
and at last get out, either at the collar or at the
sleeve. These movements are made by the
erect and projecting bristles with which the
seeds are armed, moving always in one
direction, like feet. The seeds of the sterile oat
(Avena nuda), after it has been gathered into
the barn, will wander out of their seed-cups, and,
if the weather is damp, march off in a body, like
a regiment of flies to the nearest wall, where
they will fix and take root. The explanation
of this apparently marvellous phenomenon is
extremely simple. Each grain is surmounted
by a long spiral bristle or awn, which is very
sensitive to every change of weather, and which
lengthens or contracts according as the air is
moist or dry. Thus, a forward motion is
produced like a snail putting out its body and then
pulling its shell after it. The seed is prevented
from going backwards, by the small spines placed
backwards covering the awn. If the seeds or
spores of any of the ferns are dropped on a piece
of paper and examined with a microscope, they
are seen to jump about and disperse themselves
like mites or small insects.

Some plants propagate by means of their roots
and sprouts. The mangrove fig-tree (Rhizophora
mangle) is found growing on the low
marshy parts of all tropical sea-shores. The
fruit germinates in the seed-cup while hanging
on the tree, and grows downwards until it
reaches the ground, where it takes root in the
mud. Each plant in its turn multiplies and
spreads in the same way; and Linnæus asserts
that a single plant, if preserved from destruction,
would, in course of time, multiply so as to
cover the entire inhabitable surface of our
globe.

Linnæus, keeping within reasonable limits,
and calculating what would be the effect of a
single plant producing constantly only two
successful bearing seeds each season, finds that in
twenty years there would be one hundred and
ninety-one thousand two hundred individuals.
"What then," he exclaims, "would be the
astonishing effect of such a multiplication
continued over more than six thousand years!"

About the year 1660, the Christian Fathers
at Paris possessed a root of barley, bearing forty-
nine stalks and more than eighteen thousand
seeds. Ray counted thirty-two thousand seeds
in a poppy-head, and three hundred and sixty