The seeds thus produced were self-fertilised, for they were fertilised with pollen from the same plant, but it will have been a mere chance whether with pollen from the same flowers. Both lots of seeds, after germinating on sand, were planted in pairs on the opposite sides of four pots, which were kept in the greenhouse. When the plants were a little over a foot in height they were measured, and the crossed plants averaged 13.38, and the self-fertilised 12.29 inches in height; or as 100 to 92.

When in full flower they were again measured to the extremities of their culms, as shown in Table 6/98.

TABLE 6/98. Phalaris canariensis.

Heights of plants measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 42 2/8 : 41 2/8.
Pot 1 : 39 6/8 : 45 4/8.

Pot 2 : 37 : 31 6/8.
Pot 2 : 49 4/8 : 37 2/8.
Pot 4 : 29 : 42 3/8.
Pot 2 : 37 : 34 7/8.

Pot 3 : 37 6/8 : 28.
Pot 3 : 35 4/8 : 28.
Pot 3 : 43 : 34.

Pot 4 : 40 2/8 : 35 1/8.
Pot 4 : 37 : 34 4/8.

Total : 428.00 : 392.63.

The eleven crossed plants now averaged 38.9, and the eleven self-fertilised plants 35.69 inches in height; or as 100 to 92, which is the same ratio as before. Differently to what occurred with the maize, the crossed plants did not flower before the self-fertilised; and though both lots flowered very poorly from having been kept in pots in the greenhouse, yet the self-fertilised plants produced twenty-eight flower-heads, whilst the crossed produced only twenty!

Two long rows of the same seeds were sown out of doors, and care was taken that they were sown in nearly equal number; but a far greater number of the crossed than of the self-fertilised seeds yielded plants. The self-fertilised plants were in consequence not so much crowded as the crossed, and thus had an advantage over them. When in full flower, the twelve tallest plants were carefully selected from both rows and measured, as shown in Table 6/99.

TABLE 6/99. Phalaris canariensis (growing in the open ground).

Heights of plants measured in inches.

Column 1: Crossed Plants, twelve tallest.

Column 2: Self-fertilised Plants, twelve tallest.

34 1/8 : 35 2/8.
35 7/8 : 31 1/8.
36 : 33.
35 5/8 : 32.
35 5/8 : 31 5/8.
36 1/8 : 36.
36 6/8 : 33.
38 6/8 : 32.
36 2/8 : 35 1/8.
35 5/8 : 33 5/8.
34 1/8 : 34 2/8.
34 5/8 : 35.

Total : 429.5 : 402.0.

The twelve crossed plants here average 35.78, and the twelve self-fertilised 33.5 inches in height; or as 100 to 93. In this case the crossed plants flowered rather before the self-fertilised, and thus differed from those growing in the pots.]

CHAPTER VII.

SUMMARY OF THE HEIGHTS AND WEIGHTS OF THE CROSSED AND SELF-FERTILISED PLANTS.

Number of species and plants measured. Tables given. Preliminary remarks on the offspring of plants crossed by a fresh stock. Thirteen cases specially considered. The effects of crossing a self-fertilised plant either by another self-fertilised plant or by an intercrossed plant of the old stock. Summary of the results. Preliminary remarks on the crossed and self-fertilised plants of the same stock. The twenty-six exceptional cases considered, in which the crossed plants did not exceed greatly in height the self-fertilised. Most of these cases shown not to be real exceptions to the rule that cross-fertilisation is beneficial. Summary of results. Relative weights of the crossed and self-fertilised plants.

The details which have been given under the head of each species are so numerous and so intricate, that it is necessary to tabulate the results. In Table 7/A, the number of plants of each kind which were raised from a cross between two individuals of the same stock and from self-fertilised

Charles Darwin

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