Column 2: Legitimate union. Short-styled oxlip, by pollen of long-styled primrose: 26 flowers fertilised, produced six capsules, containing 16, 20, 5, 10, 19, and 24 seeds. Average 15.7. Many of the seeds very poor, some good.

Column 3: Illegitimate union. Long-styled oxlip, by pollen of long-styled primrose: 11 flowers fertilised, produced four capsules, containing 10, 7, 5, and 6 wretched seeds. Average 7.0.

Column 4: Legitimate union. Long-styled oxlip, by pollen of short-styled primrose: 5 flowers fertilised, produced five capsules, containing 26, 32, 23, 28, and 34 seeds. Average 28.6.

TABLE 2.17. Both forms of the Cowslip crossed with Pollen of both forms of the Oxlip.

Column 1: Illegitimate union. Short-styled cowslip, by pollen of short-styled oxlip: 8 flowers fertilised, did not produce one capsule.

Column 2: Legitimate union. Long-styled cowslip, by pollen of short-styled oxlip: 8 flowers fertilised, produced one capsule, containing 26 seeds.

Column 3: Illegitimate union. Long-styled cowslip, by pollen of long-styled oxlip: 8 flowers fertilised, produced three capsules, containing 5, 6 and 14 seeds. Average 8.3.

Column 4: Legitimate union. Short-styled cowslip, by pollen of long-styled oxlip: 8 flowers fertilised, produced 8 capsules, containing 58, 38, 31, 44, 23, 26, 37, and 66 seeds. Average 40.4.

TABLE 2.18. Both forms of the Primrose crossed with Pollen of both forms of the Oxlip.

Column 1: Illegitimate union. Short-styled primrose, by pollen of short-styled oxlip: 8 flowers fertilised, did not produce one capsule.

Column 2: Legitimate union. Long-styled primrose, by pollen of short-styled oxlip: 8 flowers fertilised, produced two capsules, containing 5 and 2 seeds.

Column 3: Illegitimate union. Long-styled primrose, by pollen of long-styled oxlip: 8 flowers fertilised, produced 8 capsules, containing 15, 7, 12, 20, 22, 7, 16, and 13 seeds. Average 14.0.

Column 4: Legitimate union. Short-styled primrose, by pollen of long-styled oxlip: 8 flowers fertilised, produced 4 capsules, containing 52, 52, 42, and 49 seeds, some good and some bad. Average 48.7.

We see in Tables 2/14 to 2/18 the number of capsules and of seeds produced, by crossing both forms of the oxlip in a legitimate and illegitimate manner with one another, and with the two forms of the primrose and cowslip. I may premise that the pollen of two of the short-styled oxlips consisted of nothing but minute aborted whitish cells; but in the third short-styled plant about one- fifth of the grains appeared in a sound condition. Hence it is not surprising that neither the short-styled nor the long-styled oxlip produced a single seed when fertilised with this pollen. Nor did the pure cowslips or primroses when illegitimately fertilised with it; but when thus legitimately fertilised they yielded a few good seeds. The female organs of the short-styled oxlips, though greatly deteriorated in power, were in a rather better condition than the male organs; for though the short-styled oxlips yielded no seed when fertilised by the long-styled oxlips, and hardly any when illegitimately fertilised by pure cowslips or primroses, yet when legitimately fertilised by these latter species, especially by the long-styled primrose, they yielded a moderate supply of good seed.

The long-styled oxlip was more fertile than the three short-styled oxlips, and about half its pollen-grains appeared sound. It bore no seed when legitimately fertilised by the short-styled oxlips; but this no doubt was due to the badness of the pollen of the latter; for when illegitimately fertilised (Table 2.14) by its own pollen it produced some good seeds, though much fewer than self- fertilised cowslips or primroses would have produced. The long-styled oxlip likewise yielded a very low average of seed, as may be seen in the third compartment of Tables 2.15 to 2.18, when illegitimately fertilised by, and when illegitimately fertilising, pure cowslips and primroses. The four corresponding legitimate unions, however, were moderately fertile, and one (namely that between a short-styled cowslip and the long-styled oxlip in Table 2.17) was nearly as fertile as if both parents had been pure.

The Different Forms of Flowers on Plants of the Same Species Page 30

19th Century English Literature

Charles Darwin

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Charles Darwin

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