The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom Part 42

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 23 4/8 : 17 3/8.

Pot 1 : 12 : 20 3/8.

Pot 1 : 21 : 20.

Pot 2 : 22 : 20.

Pot 2 : 19 1/8 : 18 3/8.

Pot 2 : 21 4/8 : 18 5/8.

Pot 3 : 22 1/8 : 18 5/8.

Pot 3 : 20 3/8 : 15 2/8.

Pot 3 : 18 2/8 : 16 4/8.

Pot 3 : 21 5/8 : 18.

Pot 3 : 23 2/8 : 16 2/8.

Pot 4 : 21 : 18.

Pot 4 : 22 1/8 : 12 6/8.

Pot 4 : 23 : 15 4/8.

Pot 4 : 12 : 18.

Total : 302.88 : 263.63.

The fifteen crossed plants here average 20.19, and the fifteen self-fertilised plants 17.57 inches in height; or as 100 to 87. Mr.

Galton made a graphical representation, in accordance with the method described in the introductory chapter, of the above measurements, and adds the words "very good" to the curves thus formed.

Shortly afterwards one of the crossed plants in Pot 1 died; another became much diseased and stunted; and the third never grew to its full height. They seemed to have been all injured, probably by some larva gnawing their roots. Therefore all the plants on both sides of this pot were rejected in the subsequent measurements. When the plants were fully grown they were again measured to the tips of the highest leaves, and the eleven crossed plants now averaged 68.1, and the eleven self-fertilised plants 62.34 inches in height; or as 100 to 91. In all four pots a crossed plant flowered before any one of the self-fertilised; but three of the plants did not flower at all. Those that flowered were also measured to the summits of the male flowers: the ten crossed plants averaged 66.51, and the nine self-fertilised plants 61.59 inches in height; or as 100 to 93.

A large number of the same crossed and self-fertilised seeds were sown in the middle of the summer in the open ground in two long rows. Very much fewer of the self-fertilised than of the crossed plants produced flowers; but those that did flower, flowered almost simultaneously. When fully grown the ten tallest plants in each row were selected and measured to the tips of their highest leaves, as well as to the summits of their male flowers. The crossed averaged to the tips of their leaves 54 inches in height, and the self-fertilised 44.65, or as 100 to 83; and to the summits of their male flowers, 53.96 and 43.45 inches; or as 100 to 80.

Phalaris canariensis.

Hildebrand has shown in the paper referred to under the last species, that this hermaphrodite gra.s.s is better adapted for cross-fertilisation than for self-fertilisation. Several plants were raised in the greenhouse close together, and their flowers were mutually intercrossed.

Pollen from a single plant growing quite separately was collected and placed on the stigmas of the same plant. 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.