Thus the offspring from both unions can be compared quite fairly, free from any doubt from the injurious effects of an illegitimate union.
The plants on which I experimented had been raised during two successive generations from spontaneously self-fertilised seeds produced by plants under a net; and as the variety is highly self-fertile, its progenitors in Edinburgh may have been self-fertilised during some previous generations. Several flowers on two of my plants were legitimately crossed with pollen from a short-styled common cowslip growing almost wild in my orchard; so that the cross was between plants which had been subjected to considerably different conditions. Several other flowers on the same two plants were allowed to fertilise themselves under a net; and this union, as already explained, is a legitimate one.
The crossed and self-fertilised seeds thus obtained were sown thickly on the opposite sides of three pots, and the seedlings thinned, so that an equal number were left on the two sides. The seedlings during the first year were nearly equal in height, excepting in Pot 3, Table 6/94, in which the self-fertilised plants had a decided advantage. In the autumn the plants were bedded out, in their pots; owing to this circumstance, and to many plants growing in each pot, they did not flourish, and none were very productive in seeds. But the conditions were perfectly equal and fair for both sides. In the following spring I record in my notes that in two of the pots the crossed plants are "incomparably the finest in general appearance," and in all three pots they flowered before the self-fertilised. When in full flower the tallest flower-stem on each side of each pot was measured, and the number of the flower-stems on both sides counted, as shown in Table 6/94. The plants were left uncovered, and as other plants were growing close by, the flowers no doubt were crossed by insects. When the capsules were ripe they were gathered and counted, and the result is likewise shown in Table 6/94.
TABLE 6/94. Primula veris (equal-styled, red-flowered variety).
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Height of tallest flower-stem: crossed Plants.
Column 3: Number of Flower-stems: crossed Plants.
Column 4: Number of good capsules: crossed Plants.
Column 5: Height of tallest flower-stem: self-fertilised Plants.
Column 6: Number of Flower-stems: self-fertilised Plants.
Column 7: Number of good capsules: self-fertilised Plants.
Pot 1 : 10 : 14 : 163 : 6 4/8 : 6 : 6.
Pot 2 : 8 4/8 : 12 : * : 5 : 2 : 0. *Several, not counted.
Pot 3 : 7 4/8 : 7 : 43 : 10 4/8 : 5 : 26.
Totals : 26.0 : 33 : 206 : 22.0 : 13 : 32.
The average height of the three tallest flower-stems on the crossed plants is 8.66 inches, and that of the three on the self-fertilised plants 7.33 inches; or as 100 to 85.
All the crossed plants together produced thirty-three flower-stems, whilst the self-fertilised bore only thirteen. The number of the capsules were counted only on the plants in Pots 1 and 3, for the self-fertilised plants in Pot 2 produced none; therefore those on the crossed plants on the opposite side were not counted. Capsules not containing any good seeds were rejected. The crossed plants in the above two pots produced 206, and the self-fertilised in the same pots only 32 capsules; or as 100 to 15. Judging from the previous generations, the extreme unproductiveness of the self-fertilised plants in this experiment was wholly due to their having been subjected to unfavourable conditions, and to severe competition with the crossed plants; for had they grown separately in good soil, it is almost certain that they would have produced a large number of capsules. The seeds were counted in twenty capsules from the crossed plants, and they averaged 24.75; whilst in twenty capsules from the self-fertilised plants the average was 17.65; or as 100 to 71.