Part 19 (1/2)

From the three forms occurring in approximately equal numbers in a state of nature, and from the results of sowing seed naturally produced, there is reason to believe that each form, when legitimately fertilised, reproduces all three forms in about equal numbers. Now, we have seen (and the fact is a very singular one) that the fifty-six plants produced from the long-styled form, illegitimately fertilised with pollen from the same form (Cla.s.s 1 and 2), were all long-styled. The short-styled form, when self-fertilised (Cla.s.s 3), produced eight short-styled and one long-styled plant; and the mid-styled form, similarly treated (Cla.s.s 4), produced three mid-styled and one long-styled offspring; so that these two forms, when illegitimately fertilised with pollen from the same form, evince a strong, but not exclusive, tendency to reproduce the parent-form.

When the short-styled form was illegitimately fertilised by the long-styled form (Cla.s.s 5), and again when the mid-styled was illegitimately fertilised by the long-styled (Cla.s.s 6), in each case the two parent-forms alone were reproduced.

As thirty-seven plants were raised from these two unions, we may, with much confidence, believe that it is the rule that plants thus derived usually consist of both parent-forms, but not of the third form. When, however, the mid-styled form was illegitimately fertilised by the longest stamens of the short-styled (Cla.s.s 7), the same rule did not hold good; for the seedlings consisted of all three forms. The illegitimate union from which these latter seedlings were raised is, as previously stated, singularly fertile, and the seedlings themselves exhibited no signs of sterility and grew to their full height. From the consideration of these several facts, and from a.n.a.logous ones to be given under Oxalis, it seems probable that in a state of nature the pistil of each form usually receives, through the agency of insects, pollen from the stamens of corresponding height from both the other forms. But the case last given shows that the application of two kinds of pollen is not indispensable for the production of all three forms. Hildebrand has suggested that the cause of all three forms being regularly and naturally reproduced, may be that some of the flowers are fertilised with one kind of pollen, and others on the same plant with the other kind of pollen. Finally, of the three forms, the long-styled evinces somewhat the strongest tendency to reappear amongst the offspring, whether both, or one, or neither of the parents are long-styled.

[TABLE 5.30. Tabulated results of the fertility of the foregoing illegitimate plants, when legitimately fertilised, generally by illegitimate plants, as described under each experiment. Plants 11, 12 and 13 are excluded, as they were illegitimately fertilised.

NORMAL STANDARD OF FERTILITY OF THE THREE FORMS, WHEN LEGITIMATELY AND NATURALLY FERTILISED.

Column 1: Form.

Column 2: Average number of seeds per capsule.

Column 3: Maximum number in any one capsule.

Column 4: Minimum number in any one capsule.

Long-styled : 93 : 159 : No record was kept as all very poor capsules were rejected.

Mid-styled : 130 : 151 : No record was kept as all very poor capsules were rejected.

Short-styled : 83.5 : 112 : No record was kept as all very poor capsules were rejected.

TABLE 5.30. Continued.

CLa.s.s 1 AND CLa.s.s 2.--ILLEGITIMATE PLANTS RAISED FROM LONG-STYLED PARENTS FERTILISED WITH POLLEN FROM OWN-FORM MID-LENGTH OR SHORTEST STAMENS.

Column 1: Number (name) of plant.

Column 2: Form.

Column 3: Average number of seeds per capsule.

Column 4: Maximum number of seeds in any one capsule.

Column 5: Minimum number of seeds in any one capsule.

Column 6: Average number of seeds, expressed as the percentage of the normal standard.

1 : Long-styled : 0 : 0 : 0 : 0.

2 : Long-styled : 4.5 : ? : 0 : 5.

3 : Long-styled : 4.5 : ? : 0 : 5.

4 : Long-styled : 4.5 : ? : 0 : 5.

5 : Long-styled : 0 or 1 : 2 : 0 : 0 or 1.

6 : Long-styled : 0 : 0 : 0 : 0.

7 : Long-styled : 36.1 : 47 : 22 : 39.

8 : Long-styled : 41.1 : 73 : 11 : 44.

9 : Long-styled : 57.1 : 86 : 23 : 61.

10 : Long-styled : 44.2 : 69 : 25 : 47.

CLa.s.s 3. ILLEGITIMATE PLANTS RAISED FROM SHORT-STYLED PARENTS FERTILISED WITH POLLEN FROM OWN-FORM SHORTEST STAMENS.

14 : Short-styled : 28.3 : 51 : 11 : 33.

15 : Short-styled : 32.6 : 49 : 20 : 38.

16 : Short-styled : 77.8 : 97 : 60 : 94.

17 : Long-styled : 76.3 : 88 : 57 : 82.