Secondly, eleven flowers on the red variety were castrated whilst young and fertilised with pollen from the blue variety, and this cross evidently much increased their fertility; for the eleven flowers yielded seven capsules, which contained on an average twice as many good seeds as before, namely, 12.7; with a maximum in two of the capsules of seventeen seeds. Therefore these crossed capsules yielded seeds compared with those in the foregoing self-fertilised capsules, as 100 to 48. These seeds were also conspicuously larger than those from the cross between two individuals of the same red variety, and germinated much more freely. The flowers on most of the plants produced by the cross between the two-coloured varieties (of which several were raised), took after their mother, and were red-coloured. But on two of the plants the flowers were plainly stained with blue, and to such a degree in one case as to be almost intermediate in tint.

The crossed seeds of the two foregoing kinds and the self-fertilised were sown on the opposite sides of two large pots, and the seedlings were measured when fully grown, as shown in Tables 6/92a and 6/92b.

TABLE 6/92a. Anagallis collina: Red variety crossed by a distinct plant of the red variety, and red variety self-fertilised.

Heights of plants measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 23 4/8 : 15 4/8. Pot 1 : 21 : 15 4/8. Pot 1 : 17 2/8 : 14.

Total : 61.75 : 45.00.

TABLE 6/92b. Anagallis collina: Red variety crossed by blue variety, and red variety self-fertilised.

Heights of plants measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 2 : 30 4/8 : 24 4/8. Pot 2 : 27 3/8 : 18 4/8. Pot 2 : 25 : 11 6/8.

Total : 82.88 : 54.75.

Total of both lots: : 144.63 : 99.75.

As the plants of the two lots are few in number, they may be run together for the general average; but I may first state that the height of the seedlings from the cross between two individuals of the red variety is to that of the self-fertilised plants of the red variety as 100 to 73; whereas the height of the crossed offspring from the two varieties to the self-fertilised plants of the red variety is as 100 to 66. So that the cross between the two varieties is here seen to be the most advantageous. The average height of all six crossed plants in the two lots taken together is 48.20, and that of the six self-fertilised plants 33.25; or as 100 to 69.

These six crossed plants produced spontaneously twenty-six capsules, whilst the six self-fertilised plants produced only two, or as 100 to 8. There is therefore the same extraordinary difference in fertility between the crossed and self-fertilised plants as in the last genus, Cyclamen, which belongs to the same family of the Primulaceae.

Primula veris. British flora. (var. officinalis, Linn.).

THE COWSLIP.

Most of the species in this genus are heterostyled or dimorphic; that is, they present two forms,--one long-styled with short stamens, and the other short-styled with long stamens. (6/6. See my paper 'On the Two Forms or Dimorphic Condition in the Species of Primula' in 'Journal of the Proceedings of the Linnean Society' volume 6 1862 page 77. A second paper, to which I presently refer 'On the Hybrid-like Nature of the Offspring from the Illegitimate Unions of Dimorphic and Trimorphic Plants' was published in volume 10 1867 page 393 of the same journal.) For complete fertilisation it is necessary that pollen from the one form should be applied to the stigma of the other form; and this is effected under nature by insects. Such unions, and the seedlings raised from them, I have called legitimate. If one form is fertilised with pollen from the same form, the full complement of seed is not produced; and in the case of some heterostyled genera no seed at all is produced. Such unions, an

Charles Darwin

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