ILLEGITIMATE PLANTS RAISED FROM MID-STYLED PARENTS FERTILISED WITH POLLEN FROM THE SHORTEST STAMENS OF THE LONG-STYLED FORM.

I raised from this union twenty-five plants, which proved to be seventeen long- styled and eight mid-styled, but not one short-styled. None of these plants were in the least dwarfed. I examined, during the highly favourable season of 1866, the pollen of four plants: in one mid-styled plant, some of the anthers of the longest stamens were contabescent, but the pollen-grains in the other anthers were mostly sound, as they were in all the anthers of the shortest stamens; in two other mid-styled and in one long-styled plant many of the pollen-grains were small and shrivelled; and in the latter plant as many as a fifth or sixth part appeared to be in this state. I counted the seeds in five plants (Numbers 26 to 30), of which two were moderately sterile and three fully fertile.

[PLANT 26.

This mid-styled plant was freely and legitimately fertilised, during the rather unfavourable year 1864, by numerous surrounding legitimate and illegitimate plants. It yielded an average, from ten capsules, of 83.5 seeds, with a maximum of 110 and a minimum of 64, thus attaining 64 per cent of the normal fertility. During the highly favourable year 1866, it was freely and legitimately fertilised by illegitimate plants belonging to the present Class and to Class 5, and yielded an average, from eight capsules, of 86 seeds, with a maximum of 109 and a minimum of 61, and thus attained 66 per cent of the normal fertility. This was the plant with some of the anthers of the longest stamens contabescent as above mentioned.

PLANT 27.

This mid-styled plant, fertilised during 1864 in the same manner as the last, yielded an average, from ten capsules, of 99.4 seeds, with a maximum of 122 and a minimum of 53, thus attaining to 76 per cent of the normal fertility. If the season had been more favourable, its fertility would probably have been somewhat greater, but, judging from the last experiment, only in a slight degree.

PLANT 28.

This mid-styled plant, when legitimately fertilised during the favourable season of 1866, in the manner described under Number 26, yielded an average, from eight capsules, of 89 seeds, with a maximum of 119 and a minimum of 69, thus producing 68 per cent of the full number of seeds. In the pollen of both sets of anthers, nearly as many grains were small and shrivelled as sound.

PLANT 29.

This long-styled plant was legitimately fertilised during the unfavourable season of 1864, in the manner described under Number 26, and yielded an average, from ten capsules, of 84.6 seeds, with a maximum of 132 and a minimum of 47, thus attaining to 91 per cent of the normal fertility. During the highly favourable season of 1866, when fertilised in the manner described under Number 26, it yielded an average, from nine capsules (one poor capsule having been excluded), of 100 seeds, with a maximum of 121 and a minimum of 77. This plant thus exceeded the normal standard, and produced 107 per cent of seeds. In both sets of anthers there were a good many bad and shrivelled pollen-grains, but not so many as in the last-described plant.

Plant 30.

This long-styled plant was legitimately fertilised during 1866 in the manner described under Number 26, and yielded an average, from eight capsules, of 94 seeds, with a maximum of 106 and a minimum of 66; so that it exceeded the normal standard, yielding 101 per cent of seeds.

Plant 31.

Some flowers on this long-styled plant were artificially and legitimately fertilised by one of its brother illegitimate mid-styled plants; and five capsules yielded an average of 90.6 seeds, with a maximum of 97 and a minimum of 79. Hence, as far as can be judged from so few capsules, this plant attained, under these favourable circumstances, 98 per cent of the normal standard.]

CLASS 7. ILLEGITIMATE PLANTS RAISED FROM MID-STYLED PARENTS FERTILISED WITH POLLEN FROM THE LONGEST STAMENS OF THE SHORT-STYLED FORM.

It was shown in the last chapter that the union from which these illegitimate plants were raised is far more fertile than any other illegitimate union; for the mid-styled parent, when thus fertilised, yielded an average (all very poor capsules being excluded) of 102.8 seeds, with a maximum of 130; and the seedlings in the present class likewise have their fertility not at all lessened.

Charles Darwin

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