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Darwin on Cross-fertilization of Plants.

A copy of Mr. Darwin's new work on cross-fertilization has reached us and, like all previous works by the same author, we find it full of interesting facts, many of which are of great value to horticulturists. The object of the work is to show the benefits of cross-fertilization, and especially is this shown to be the case when either the pollen or seed-bearing parent is brought from a distance or from a fresh stock, for as Mr. Darwin himself puts it "the advantages of cross-fertilization do not follow from some mysterious virtue in the mere union of two distinct individuals, but from such individuals having been subjected during previous generations to different conditions, or to their having varied in a manner commonly called spontaneous, so that in either case their sexual elements have been in some degree differentiated; and secondly, that the injury from self- fertilization follows from the want of such differentiation in the sexual elements." Self-fertilization, however, has one advantage, for by practicing it for six or seven generations under similar conditions of growth, the seedlings obtained are, to all appearance, perfectly alike, or as gardeners put it they "come true", a condition often highly desirable. We thus see that cross-fertilization by insect agency is likely to originate new forms, while self-fertilizing plants, on the other hand, are more likely to possess fixed characters or sameness of habit and colour. We shall refer to this work again, but in the meantime we strongly recommend it to the notice of all who are interested in the higher branches of plant culture and improvement.

B.