thout which its
living principle is destroyed.--_Smith_.

_Why is fructification so important to plants?_

Because it continues them by seeds, and, according to Sir James Smith,
"all other modes of propagation are but the extension of an individual,
and, sooner or later, terminate in its total extinction." Dr. Drummond is
of a contrary opinion, and quotes the following fact:--"In South America
there is a species of bamboo which forms forests in the marshes of many
leagues in extent, and yet Mutis, who botanized for nearly twenty
years in the parts where it grows, was never able to detect the
fructifications."--_Humboldt_.

The produce of vegetable seeds in a hundred-fold degree is common, and
many trees and shrubs bring forth their fruit by thousands. A single plant
of the poppy will produce above 30,000 seeds; and, of tobacco, above
40,000; and Buffon remarks, that from the seeds of a single elm-tree, one
hundred thousand young elms may be raised from the product of one year.
Some ferns, it is said, produce their seeds by millions.

_Why should seeds be uniformly kept dry before sown?_

Because the least damp will cause an attempt at vegetation, when the seeds
necessarily die, as the process cannot, as they are situated, go on.

_Why, in summer, is continued watering required to newly sown seeds?_

Because, if the soil is only moistened at the time of sowing, it induces
the projection of the radicle, or first root, which, in very parching
weather, and in clayey cutting soil, withers away, and the crop is
consequently lost, for want of a continued supply of moisture.

_Why is selection important for procuring abundance of genuine seeds?_

Because we may then choose the most vigorous plants, which naturally prove
of greater fecundity. Thus, in 1823, Mr. Shirreff marked one vigorous
wheat plant, near the centre of a field, which produced him 2,473 grains.
These were dibbled in the autumn of the same year, the produce sown
broadcast the second and third years, and the fourth harvest produced
forty quarters of sound grain. A fine purple-topped Swedish turnip
produced 100,296 grains, which was seed enough for five imperial acres,
and thus, in three years, one turnip would produce seed enough for Great
Britain for a year.--_Quarterly Journal of Agriculture._

_Why are winds the great agents by which seeds are diffused?_

Because seeds are, as it were, provided with various wings for seizing on
the breeze. The thist