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 thistle and dandelion are familiar examples of this mode of dissemination.  “How little,” Sir J.E.  Smith observes, “are children aware, as they blow away the seeds of dandelion, or stick burs in sport upon each other’s clothes, that they are fulfilling one of the great ends of nature.”  Dr. Woodward calculates, that one seed of the common spear thistle will produce “at the first crop, twenty-four thousand, and consequently five hundred and twenty-six millions of seeds, at the second.”