Therefore the crossed plants did not exceed in weight the self-fertilised plants in nearly so great a degree as those growing in the pots, owing probably to the latter having been subjected to more severe mutual competition. On the other hand, they exceeded the self-fertilised in height in a slightly greater degree.

Reseda odorata.

Plants of the common mignonette were raised from purchased seed, and several of them were placed under separate nets. Of these some became loaded with spontaneously self-fertilised capsules; others produced a few, and others not a single one. It must not be supposed that these latter plants produced no seed because their stigmas did not receive any pollen, for they were repeatedly fertilised with pollen from the same plant with no effect; but they were perfectly fertile with pollen from any other plant. Spontaneously self-fertilised seeds were saved from one of the highly self-fertile plants, and other seeds were collected from the plants growing outside the nets, which had been crossed by the bees. These seeds after germinating on sand were planted in pairs on the opposite sides of five pots. The plants were trained up sticks, and measured to the summits of their leafy stems--the flower-stems not being included. We here have the result:--

TABLE 4/37. Reseda odorata (seedlings from a highly self-fertile plant).

Heights of plants to the summits of the leafy stems, flower-stems not included, measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 20 7/8 : 22 4/8. Pot 1 : 34 7/8 : 28 5/8. Pot 1 : 26 6/8 : 23 2/8. Pot 1 : 32 6/8 : 30 4/8.

Pot 2 : 34 3/8 : 28 5/8. Pot 2 : 34 5/8 : 30 5/8. Pot 2 : 11 6/8 : 23. Pot 2 : 33 3/8 : 30 1/8.

Pot 3 : 17 7/8 : 4 4/8. Pot 3 : 27 : 25. Pot 3 : 30 1/8 : 26 3/8. Pot 3 : 30 2/8 : 25 1/8.

Pot 4 : 21 5/8 : 22 6/8. Pot 4 : 28 : 25 4/8. Pot 4 : 32 5/8 : 15 1/8. Pot 4 : 32 3/8 : 24 6/8.

Pot 5 : 21 : 11 6/8. Pot 5 : 25 2/8 : 19 7/8. Pot 5 : 26 6/8 : 10 4/8.

Total : 522.25 : 428.50.

The average height of the nineteen crossed plants is here 27.48, and that of the nineteen self-fertilised 22.55 inches; or as 100 to 82. All these plants were cut down in the early autumn and weighed: the crossed weighed 11.5 ounces, and the self-fertilised 7.75 ounces, or as 100 to 67. These two lots having been left freely exposed to the visits of insects, did not present any difference to the eye in the number of seed-capsules which they produced.

The remainder of the same two lots of seeds were sown in two adjoining rows in the open ground; so that the plants were exposed to only moderate competition. The eight tallest on each side were measured, as shown in Table 4/38.

TABLE 4/38. Reseda odorata, growing in the open ground.

Heights of plants measured in inches.

Column 1: Crossed Plants.

Column 2: Self-fertilised Plants.

24 4/8 : 26 5/8. 27 2/8 : 25 7/8. 24 : 25. 26 6/8 : 28 3/8. 25 : 29 7/8. 26 2/8 : 25 7/8. 27 2/8 : 26 7/8. 25 1/8 : 28 2/8.

Total : 206.13 : 216.75

The average height of the eight crossed plants is 25.76, and that of the eight self-fertilised 27.09; or as 100 to 105.

We here have the anomalous result of the self-fertilised plants being a little taller than the crossed; of which fact I can offer no explanation. It is of course possible, but not probable, that the labels may have been interchanged by accident.

Another experiment was now tried: all the self-fertilised capsules, though very few in number, were gathered from one of the semi-self-sterile plants under a net; and as several flowers on this same plant had been fertilised with pollen from a distinct individual, crossed seeds were thus obtained. I expected that the seedlings from this semi-self-sterile plant would have profited in a higher degree from a cross, than did the seedlings from the fully self-fertile plants.

The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom Page 61

19th Century English Literature

Charles Darwin

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Charles Darwin

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