1086. Permanency of metamorphoses. 'It is a general law of nature, that seeds will perpetuate a species but not a variety ; and this is no doubt true, if rightly considered ; and yet, it may be urged, if this be so, how have the varieties, well known to gardeners and agriculturists, for many years been unceasingly carried on from generation to generation without change ? The long red, and round white radishes of the markets, for instance, have been known from time immemorial in the same state in which they now exist. The answer is this. A species will perpetuate itself from seed for ever under any circumstances, and left to the simple aid of nature : but accidental varieties cannot be so perpetuated; if suffered to become wild, they very soon revert to the form from which they originally sprung. It is necessary that they should be cultivated with the utmost care; that seed should be saved from those individuals only in which the marks of the variety are most distinctly traced; and all plants that indicate any disposition to cast off their peculiar characteristics should be rejected. If this is carefully done, the existence of any variety of annual or perennial plant may undoubtedly be prolonged through many generations; but in woody plants this scarcely happens, it being a rare occurrence to find any variety of tree or shrub producing its like when increased by seed.' (Lindl. Introd., p. 526.)
