[6]

Arachis hypogaea circumnutation of leaf 1878

689

Chap. _10

on the effects of cross-fertilising flowers, which have not been castrated and which are highly self-fertile, with pollen from another individual of the same variety, we may conclude that the pollen which is carried brought by insects or by the wind from one a distinct plant to another will generally prevent the action of that from, the same flowers, each plant's own pollen from native, even though it may have been applied some time before: and thus the intercrossing of plants in a state of nature will be greatly favoured or ensured.

Of all tThe case known to me, that of a great tree covered with innumerable hermaphrodite flowers seems at first sight strongly opposed to the belief in the frequency of intercrosses between distinct individuals. A cross between The flowers which grow on the opposite sides of such tree, may perhaps be beneficial in some degree, as these will have been exposed to somewhat different conditions & a cross between them may be in some degree beneficial; but it is not probable that & a cross of this kind it would be nearly so beneficial as a cross between the flowers on distinct trees, as we may infer from the inefficiency

[Cross and self fertilisation, p. 398: "From the various facts now given on the spontaneous intercrossing of varieties growing near together, and on the effects of cross-fertilising flowers which are self-fertile and have not been castrated, we may conclude that pollen brought by insects or by the wind from a distinct plant will generally prevent the action of pollen from the same flower, even though it may have been applied some time before; and thus the intercrossing of plants in a state of nature will be greatly favoured or ensured.

The case of a great tree covered with innumerable hermaphrodite flowers seems at first sight strongly opposed to the belief in the frequency of intercrosses between distinct individuals. The flowers which grow on the opposite sides of such a tree will have been exposed to somewhat different conditions, and a cross between them may perhaps be in some degree beneficial; but it is not probable that it would be nearly so beneficial as a cross between flowers on distinct trees, as we may infer from the inefficiency of pollen taken from plants which have been propagated from the same stock, though growing on separate roots."]