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Show 222 PRIMULA VERIS. Cn.AP. VI. 168 good capsules, whilst the sel.f-fortilised phnts produced only two such flower-stems, bearmg only 6 capsules, half of which were very poor ones. So that tho fertility of the two lots, judging by the number of ca?sules, ~as a~ 100 to 3 · 5. In considering tho great difference 1n hmght and the wonderful difference in fertility between the two sets of plants, we should bear in mind that this is the result of two distinct ngcncies. The self-fertilised plants were the product of Hlcrritimate fertilisation during five succe. sive gen rations, in all of wl1ich, excepting the last, the plants had been fertilised with pollen taken from a distinct individual belonging to the same form, but which was more or less closely related. The plants had also been subjected in each generation to closely similar conditions. This treatment alone, as I know fr01n other observations, would have greatly reduced the size and fertility of tho off: pring. On the other hand, the crossed plants wore the offspring of long-styled plants of the fourth illegitimate generation legitimately crossed with pollen from a short-styled plant, which, as well as its progenitors, had been exposed to very differr.nt conditions; and this latter circumstance alone would have given great vigour to the offspring, as we may infer from the several analogous cases already given. How much proportional weight ought to be attributed to these two agencies,-the one tending to injure the self-fertilised offspring, and the other to benefit the crossed offspring,-cannot be determined. But we shall immediately see that the greater part of the benefit, as far as increased fertility is concerned, must be attributed to the cross having been made with a fresh stock. PRIMULA VERIS. Equal-styled and 'red-flowered var. I have described in my paper 'On the Illegitimate Unions of Dimorphic and Trimorphic Plants' this remarkable variety, which was sent to me from Edinburgh by 1\1r. J. Scott. It posse. sed a pistil proper to the long-styled form, and stamens proper to the short-styled form; so that it had lost the hctcrostyled or dimorphic character common to most of tho species of the genu~, and may be compared with an hermaphrodite form of a bisexual animal. Consequently the pollen and stigma of the sarrie flower are adapted for complete mutual fertilisation, instead of its being necessary that pollen should be brought from one CHAP. VI. EQUAL-STYLED V ARIE1'Y. 223 form to another, as in the common cowslip. From the stigma and anthers standing nearly on the same level, the flowers are perfectly self-fertile when insects are excluded. Owing to the fortunate existence of this variety, it is possible to fertilise its flowers in a legitimate manner with their own pollen, and to cross other flowers in a legitimate manner with pollen from another variety or fresh stock. 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 durino- o two successive generations from spontaneously self-fertilised seeds produced Ly 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 th~ckly on the opposite sides of three pots, and the seedlings thmned, so that an equal number were left on the two sides. T~e seedlings during the first year were nearly equal in he1ght, excepting in Pot III., Table XCIV., in which the selffertilised 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 selffertilised. When in full flower the tallest flower-stem on each side of each pot was measured, and the number of tho flower- . stems on both sides counted, as shown in the following table. 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 the following table:- |