If you have seen--and who has not?--the flowers of the potato-plant, you will immediately recognise the flowers of the Garden or Black Nightshade. (Fig. 19.) This noxious herb--noxious in some, but useful in other respects, and, therefore, not to be visited with too hasty a condemnation--flowers and fructifies throughout the year. Its fertility is extreme; only the severest winter-frosts can crush out its prolific life. The fruits which succeed to the flowers are smaller berries or "apples" than those of the potato. (See Fig. 20.) In the history of botany, and even in that of philosophy, the Black Nightshade (_Solanum nigrum_) has a certain interest. Thus, says M. Hoefer, both Cordus and Jean Bauhin, botanists of the sixteenth century, have described the flower of this plant as if its corolla were composed of five distinct petals. [Illustration: FIG. 21.] Where were the eyes of those great botanists? The corolla of the nightshade, like that of all the _Solanaceæ_, is plainly and obviously monopetalous,--that is, composed of a single piece; to assure yourself of this, you have but to open it out. (See Fig. 21, _b_.) It was the sharp-pointed, ovate divisions of the limb which imposed on the old observers; a fresh proof that _seeing_ and _observing_ are two very distinct things. Our vision enters into full exercise from earliest infancy; observation is not acquired until after much labour and many years. Do not forget to add, that the five stamens are brought very closely together by their elongated anthers, as is also seen in the flower of the potato-plant. (Fig. 21, _a_.) The same botanists who took our solanum for a plant with a polypetalous corolla, considered the Bitter-sweet (_Solanum dulcamara_) to be a metamorphosis of the Garden Nightshade! The former they christened the red-berried solanum (_Solanum baccis rubris_), and the latter, the black-berried solanum (_Solanum baccis nigris_). * * * * * But if we once launch into the hypothetical, we shall be unable to stop half-way. If the species of one and the same genus are the result of a transformation, why may we not assert as much of the genera of a family, or the families of an order? Thus we should arrive, step by step, at an unique type, not only for the vegetable kingdom, but for vegetables and animals, including man himself, and realise, to some extent, the ideal of the Greeks,--_unity in variety_. Be it acknowledged, however, that _we_ have no desire to rise to so lofty an elevation. The potato-plant--unknown to the ancients, inasmuch as it is a native of the New World--has not been found to lose its character since its introduction into the ancient continent; its congener, the nightshade--an old native, like every bad herb--accompanies it everywhere; but its fibrous roots are absolutely virgin of every farinaceous tubercule.