[86]

Embryonic

Jan 31 & Feb 1 & 2d

Circumnutation of radicle of Red Cabbage Radicle from 9° a.m Jan. 31' to 7° a.m Feb 2d. (Right Hand)

Fig 2 (no lettering Reduced to 1/2 scale)

[87]

100 711

Chap. 9 10

case its numerous flowers would be less liable to continued self-fertilisation.

[sheet of paper pasted on:] Finally we have seen reason to believe that all the higher plants are descended from extremely low forms which conjugated; & that the conjugating individuals differed a little from each other, ─ the one representing the male & the other the females; so that plants were aboriginally diœcious. At a very early period such lowly organised diœcious plants probably gave rise by budding either after or even even before conjugation to monœcious plants with the two sexes borne by the same individuals; & by a still closer union of the sexes to hermaphrodite plants, which are now the commonest form.*

As soon as plants grew were affixed to the ground, their pollen must have been carried by some means from flower to flower, at first almost certainly by the wind, then by pollen-devouring & afterwards next commonly by nectar-seeking insects.

During subsequent ages some few entomophilous

[Cross and self fertilisation, pp. 412-3: "Or to put the case in another way, a plant would be better fitted for development into a tree, if the sexes were separated, than if it were hermaphrodite; for in the former case its numerous flowers would be less liable to continued self-fertilisation. But it should also be observed that the long life of a tree or bush permits of the separation of the sexes, with much less risk of evil from impregnation occasionally failing and seeds not being produced, than in the case of short-lived plants. Hence it probably is, as Lecoq has remarked, that annual plants are rarely dioecious.
Finally, we have seen reason to believe that the higher plants are descended from extremely low forms which conjugated, and that the conjugating individuals differed somewhat from one another,—the one representing the male and the other the female—so that plants were aboriginally dioecious. At a very early period such lowly organised dioecious plants probably gave rise by budding to monoecious plants with the two sexes borne by the same individual; and by a still closer union of the sexes to hermaphrodite plants, which are now much the commonest form.* As soon as plants became affixed to the ground, their pollen must have been carried by some means from flower to flower, at first almost certainly by the wind, then by pollen-devouring, and afterwards by nectar-seeking insects. During subsequent ages some few entomophilous plants have been again rendered anemophilous, and some hermaphrodite plants have had their sexes again separated; and we can vaguely see the advantages of such recurrent changes under certain conditions."]