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; or as 100 to 65. But this great inequality is in part accidental, owing to some of the self-fertilised plants being very short, and to one of the crossed being very tall.
Twelve flowers on these crossed plants were again crossed, and eleven capsules were produced; of these, five were poor and six good; the latter contained by weight 3.75 grains of seeds. Twelve flowers on the self-fertilised plants were again fertilised with their own pollen and produced no less than twelve capsules, and the six finest of these contained by weight 2.57 grains of seeds. It should however be observed that these latter capsules were produced by the plants in Pot 3, which were not exposed to any competition. The seeds in the six fine crossed capsules to those in the six finest self-fertilised capsules were in weight as 100 to 68. From these seeds the plants of the next generation were raised.
CROSSED AND SELF-FERTILISED PLANTS OF THE THIRD GENERATION.
TABLE 6/78. Petunia violacea (third generation; plants very young).
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 1 4/8 : 5 6/8. Pot 1 : 1 : 4 4/8.
Pot 2 : 5 7/8 : 8 3/8. Pot 2 : 5 6/8 : 6 7/8.
Pot 3 : 4 : 5 5/8.
Pot 4 : 1 4/8 : 5 3/8.
Total : 19.63 : 36.50.
The above seeds were placed on sand, and after germinating were planted in pairs on the opposite sides of four pots; and all the remaining seeds were thickly sown on the two sides of a fifth large pot. The result was surprising, for the self-fertilised seedlings very early in life beat the crossed, and at one time were nearly double their height. At first the case appeared like that of Mimulus, in which after the third generation a tall and highly self-fertile variety appeared. But as in the two succeeding generations the crossed plants resumed their former superiority over the self-fertilised, the case must be looked at as an anomaly. The sole conjecture which I can form is that the crossed seeds had not been sufficiently ripened, and thus produced weakly plants, as occurred with Iberis. When the crossed plants were between 3 and 4 inches in height, the six finest in four of the pots were measured to the summits of their stems, and at the same time the six finest of the self-fertilised plants. The measurements are given in Table 6/78, and it may be here seen that all the self-fertilised plants exceed their opponents in height, whereas when subsequently measured the excess of the self-fertilised depended chiefly on the unusual tallness of two of the plants in Pot 2. The crossed plants here average 3.27, and the self-fertilised 6.08 inches in height; or as 100 to 186.
When fully grown they were again measured, as follows:--
TABLE 6/79. Petunia violacea (third generation; plants fully grown).
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 41 4/8 : 40 6/8. Pot 1 : 48 : 39. Pot 1 : 36 : 48.
Pot 2 : 36 : 47. Pot 2 : 21 : 80 2/8. Pot 2 : 36 2/8 : 86 2/8.