Several flowers on this plant were crossed with pollen from other flowers on the same plant, and several other flowers were fertilised with their own pollen. The seed thus produced was allowed to germinate on bare sand; and the seedlings were planted in the usual manner on the opposite sides of six pots. All the remaining seeds, whether or not in a state of germination, were sown thickly in Pot 7; the three tallest plants on each side of this latter pot being alone measured. As I was in a hurry to learn the result, some of these seeds were sown late in the autumn, but the plants grew so irregularly during the winter, that one crossed plant was 28 1/2 inches, and two others only 4, or less than 4 inches in height, as may be seen in Table 3/21. Under such circumstances, as I have observed in many other cases, the result is not in the least trustworthy; nevertheless I feel bound to give the measurements.

TABLE 3/21. Mimulus luteus.

Heights of Plants in inches:

Column 1: Number (Name) of Pot.

Column 2: Plants raised from a Cross between different Flowers on the same Plant.

Column 3: Plants raised from Flowers fertilised with their own Pollen.

Pot 1 : 17 : 17. Pot 1 : 9 : 3 1/8.

Pot 2 : 28 2/8 : 19 1/8. Pot 2 : 16 4/8 : 6. Pot 2 : 13 5/8 : 2.

Pot 3 : 4 : 15 6/8. Pot 3 : 2 2/8 : 10.

Pot 4 : 23 4/8 : 6 2/8. Pot 4 : 15 4/8 : 7 1/8.

Pot 5 : 7 : 13 4/8.

Pot 6 : 18 3/8 : 1 4/8. Pot 6 : 11 : 2.

Pot 7 : 21 : 15 1/8. Pot 7 : 11 6/8 : 11. Pot 7 : 12 1/8 : 11 2/8. Crowded.

Total : 210.88 : 140.75.

The fifteen crossed plants here average 14.05, and the fifteen self-fertilised plants 9.38 in height, or as 100 to 67. But if all the plants under ten inches in height are struck out, the ratio of the eleven crossed plants to the eight self-fertilised plants is as 100 to 82.

On the following spring, some remaining seeds of the two lots were treated in exactly the same manner; and the measurements of the seedlings are given in Table 3/22.

TABLE 3/22. Mimulus luteus.

Heights of Plants in inches:

Column 1: Number (Name) of Pot.

Column 2: Plants raised from a Cross between different Flowers on the same Plant.

Column 3: Plants raised from Flowers fertilised with their own Pollen.

Pot 1 : 15 1/8 : 19 1/8. Pot 1 : 12 : 20 5/8. Pot 1 : 10 1/8 : 12 6/8.

Pot 2 : 16 2/8 : 11 2/8. Pot 2 : 13 5/8 : 19 3/8. Pot 2 : 20 1/8 : 17 4/8.

Pot 3 : 18 7/8 : 12 6/8. Pot 3 : 15 : 15 6/8. Pot 3 : 13 7/8 : 17.

Pot 4 : 19 2/8 : 16 2/8. Pot 4 : 19 6/8 : 21 5/8.

Pot 5 : 25 3/8 : 22 5/8.

Pot 6 : 15 : 19 5/8. Pot 6 : 20 2/8 : 16 2/8. Pot 6 : 27 2/8 : 19 5/8.

Pot 7 : 7 6/8 : 7 6/8. Pot 7 : 14 : 8. Pot 7 : 13 4/8 : 7.

Pot 8 : 18 2/8 : 20 3/8. Pot 8 : 18 6/8 : 17 6/8. Pot 8 : 18 3/8 : 15 4/8. Pot 8 : 18 3/8 : 15 1/8. Crowded.

Total : 370.88 : 353.63.

Here the average height of the twenty-two crossed plants is 16.85, and that of the twenty-two self-fertilised plants 16.07; or as 100 to 95. But if four of the plants in Pot 7, which are much shorter than any of the others, are struck out (and this would be the fairest plan), the twenty-one crossed are to the nineteen self-fertilised plants in height as 100 to 100.6--that is, are equal. All the plants, except the crowded ones in Pot 8, after being measured were cut down, and the eighteen crossed plants weighed 10 ounces, whilst the same number of self-fertilised plants weighed 10 1/4 ounces, or as 100 to 102.5; but if the dwarfed plants in Pot 7 had been excluded, the self-fertilised would have exceeded the crossed in weight in a higher ratio. In all the previous experiments in which seedlings were raised from a cross between distinct plants, and were put into competition with self-fertilised plants, the former generally flowered first; but in the present case, in seven out of the eight pots a self-fertilised plant flowered before a crossed one on the opposite side.

The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom Page 39

19th Century English Literature

Charles Darwin

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Charles Darwin

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