Chapter 6 - Page 2

opposite sides of Pots 1 and 2; but only the tallest plant on each side was measured. Seeds were also sown thickly on the two sides of a large pot (3), the seedlings being afterwards thinned, so that an equal number was left on each side; the three tallest on each side being measured. The pots were kept in the greenhouse, and the plants were trained up sticks. For some time the young crossed plants had no advantage in height over the self-fertilised; but their leaves were larger. When fully grown and in flower the plants were measured, as follows:--

TABLE 6/76. Petunia violacea (first generation).

Heights of plants measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 30 : 20 4/8.

Pot 2 : 34 4/8 : 27 4/8.

Pot 3 : 34 : 28 4/8. Pot 3 : 30 4/8 : 27 4/8. Pot 3 : 25 : 26.

Total : 154 : 130.

The five tallest crossed plants here average 30.8, and the five tallest self-fertilised 26 inches in height, or as 100 to 84.

Three capsules were obtained by crossing flowers on the above crossed plants, and three other capsules by again self-fertilising flowers on the self-fertilised plants. One of the latter capsules appeared as fine as any one of the crossed capsules; but the other two contained many imperfect seeds. From these two lots of seeds the plants of the following generation were raised.

CROSSED AND SELF-FERTILISED PLANTS OF THE SECOND GENERATION.

As in the last generation, many of the self-fertilised seeds germinated before the crossed.

Seeds in an equal state of germination were planted on the opposite sides of three pots. The crossed seedlings soon greatly exceeded in height the self-fertilised. In Pot 1, when the tallest crossed plant was 10 1/2 inches high, the tallest self-fertilised was only 3 1/2 inches; in Pot 2 the excess in height of the crossed was not quite so great. The plants were treated as in the last generation, and when fully grown measured as before. In Pot 3 both the crossed plants were killed at an early age by some animal, so that the self-fertilised had no competitors. Nevertheless these two self-fertilised plants were measured, and are included in Table 6/77. The crossed plants flowered long before their self-fertilised opponents in Pots 1 and 2, and before those growing separately in Pot 3.

TABLE 6/77. Petunia violacea (Second generation).

Heights of plants measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 57 2/8 : 13 4/8. Pot 1 : 36 2/8 : 8.

Pot 2 : 44 4/8 : 33 2/8. Pot 2 : 24 : 28.

Pot 3 : 0 : 46 2/8. Pot 3 : 0 : 28 4/8.

Total : 162.0 : 157.5.

The four crossed plants average 40.5, and the six self-fertilised 26.25 inches in height;