[291 and 292]

Cotton, (nankin)

circumnutation of Cotyledons Hypocotyl Secured

[292v]

79 690

Chap. E 10

of pollen taken from plant which has been propagated from the same stock, though growing on separate roots. The number of bees which frequent certain kinds large of trees of &c when in full flower, is very great, and they may be seen flying from tree to tree more frequently than might have been expected. Nevertheless if we consider how numerous are the flowers, for instance, on a large great horse-chestnut or lime-tree, an incomparably greater larger number will of flowers must be fertilised by pollen brought from other flowers on the same tree, than from those flowers on a distinct tree. But we should bear in mind that with the horse-chestnut, for instance, only one or two or more of the several flowers on the same peduncle or none produce a seed; and that this seed is the product of one out of several ovules within the same ovarium.

Now we know from the experiments of Herbert and others* (*Variation under Domestication Ch. 17 Vol. II 2nd Edit. Vol II. p. 120) that id a flower is fertilised with pollen which more efficient pollen that than that which is applied to the other

[Cross and self fertilisation, pp. 398-9: "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. The number of bees which frequent certain kinds of trees when in full flower is very great, and they may be seen flying from tree to tree more frequently than might have been expected. Nevertheless, if we consider how numerous are the flowers, for instance, on a horse-chestnut or lime-tree, an incomparably larger number of flowers must be fertilised by pollen brought from other flowers on the same tree, than from flowers on a distinct tree. But we should bear in mind that with the horse-chestnut, for instance, only one or two of the several flowers on the same peduncle produce a seed; and that this seed is the product of only one out of several ovules within the same ovarium. Now we know from the experiments of Herbert and others* that if one flower is fertilised with pollen which is more efficient than that applied to the other flowers on the same peduncle, the latter often drop off; and it is probable that this would occur with many of the self-fertilised flowers on a large tree, if other and adjoining flowers were cross-fertilised.
* 'Variation under Domestication' chapter xvii. 2nd edition volume ii. page 120."]