We will now turn to the short-styled form: from a plant of this kind, fertilised with its own-form pollen, I raised, during February 1862, eight seedlings, seven of which were short-styled and one long-styled. They grew slowly, and never attained to the full stature of ordinary plants; some of them flowered precociously, and others late in the season. Four flowers on these short-styled seedlings and four on the one long-styled seedling were illegitimately fertilised with their own-form pollen and produced only three capsules, containing on an average 23.6 seeds, with a maximum of 29; but we cannot judge of their fertility from so few capsules; and I have greater doubts about the normal standard for this union than about any other; but I believe that rather above 25 seeds would be a fair estimate. Eight flowers on these same short- styled plants, and the one long-styled illegitimate plant were reciprocally and legitimately crossed; they produced five capsules, which contained an average of 28.6 seeds, with a maximum of 36. A reciprocal cross between legitimate plants of the two forms would have yielded an average of at least 57 seeds, with a possible maximum of 74 seeds; so that these illegitimate plants were sterile when legitimately crossed.
I succeeded in raising from the above seven short-styled illegitimate plants, fertilised with their own-form pollen, only six plants—grandchildren of the first union. These, like their parents, were of low stature, and had so poor a constitution that four died before flowering. With ordinary plants it has been a rare event with me to have more than a single plant die out of a large lot. The two grandchildren which lived and flowered were short-styled; and twelve of their flowers were fertilised with their own-form pollen and produced twelve capsules containing an average of 28.2 seeds; so that these two plants, though belonging to so weakly a set, were rather more fertile than their parents, and perhaps not in any degree sterile. Four flowers on the same two grandchildren were legitimately fertilised by a long-styled illegitimate plant, and produced four capsules, containing only 32.2 seeds instead of about 64 seeds, which is the normal average for legitimate short-styled plants legitimately crossed.
By looking back, it will be seen that I raised at first from a short-styled plant fertilised with its own-form pollen one long-styled and seven short-styled illegitimate seedlings. These seedlings were legitimately intercrossed, and from their seed fifteen plants were raised, grandchildren of the first illegitimate union, and to my surprise all proved short-styled. Twelve short-styled flowers borne by these grandchildren were illegitimately fertilised with pollen taken from other plants of the same lot, and produced eight capsules which contained an average of 21.8 seeds, with a maximum of 35. These figures are rather below the normal standard for such a union. Six flowers were also legitimately fertilised with pollen from an illegitimate long-styled plant and produced only three capsules, containing on an average 23.6 seeds, with a maximum of 35. Such a union in the case of a legitimate plant ought to have yielded an average of 64 seeds, with a possible maximum of 73 seeds.
A SUMMARY ON THE TRANSMISSION OF FORM, CONSTITUTION, AND FERTILITY OF THE ILLEGITIMATE OFFSPRING OF Primula Sinensis.
In regard to the long-styled plants, their illegitimate offspring, of which fifty-two were raised in the course of two generations, were all long-styled. (5/7. Dr. Hildebrand, who first called attention to this subject ‘Botanische Zeitung’ 1864 page 5, raised from a similar illegitimate union seventeen plants, of which fourteen were long-styled and three short-styled. From a short-styled plant illegitimately fertilised with its own pollen he raised fourteen plants, of which eleven were short-styled and three long-styled.) These plants grew vigorously; but the flowers in one instance were small, appearing as if they had reverted to the wild state. In the first illegitimate generation they were perfectly fertile, and in the second their fertility was only very slightly impaired. With respect to the short-styled plants, twenty-four out of twenty- five of their illegitimate offspring were short-styled. They were dwarfed in stature, and one lot of grandchildren had so poor a constitution that four out of six plants perished before flowering. The two survivors, when illegitimately fertilised with their own-form pollen, were rather less fertile than they ought to have been; but their loss of fertility was clearly shown in a special and unexpected manner, namely, when legitimately fertilised by other illegitimate plants: thus altogether eighteen flowers were fertilised in this manner, and yielded twelve capsules, which included on an average only 28.5 seeds, with a maximum of 45. Now a legitimate short-styled plant would have yielded, when legitimately fertilised, an average of 64 seeds, with a possible maximum of 74. This particular kind of infertility will perhaps be best appreciated by a simile: we may assume that with mankind six children would be born on an average from an ordinary marriage; but that only three would be born from an incestuous marriage. According to the analogy of Primula Sinensis, the children of such incestuous marriages, if they continued to marry incestuously, would have their sterility only slightly increased; but their fertility would not be restored by a proper marriage; for if two children, both of incestuous origin, but in no degree related to each other, were to marry, the marriage would of course be strictly legitimate, nevertheless they would not give birth to more than half the full and proper number of children.
[EQUAL-STYLED VARIETY OF Primula Sinensis.
As any variation in the structure of the reproductive organs, combined with changed function, is a rare event, the following cases are worth giving in detail. My attention was first called to the subject by observing, in 1862, a long-styled plant, descended from a self-fertilised long-styled parent, which had some of its flowers in an anomalous state, namely, with the stamens placed low down in the corolla as in the ordinary long-styled form, but with the pistils so short that the stigmas stood on a level with the anthers. These stigmas were nearly as globular and as smooth as in the short-styled form, instead of being elongated and rough as in the long-styled form. Here, then, we have combined in the same flower, the short stamens of the long-styled form with a pistil closely resembling that of the short-styled form. But the structure varied much even on the same umbel: for in two flowers the pistil was intermediate in length between that of the long and that of the short-styled form, with the stigma elongated as in the former, and smooth as in the latter; and in three other flowers the structure was in all respects like that of the long-styled form. These modifications appeared to me so remarkable that I fertilised eight of the flowers with their own pollen, and obtained five capsules, which contained on an average 43 seeds; and this number shows that the flowers had become abnormally fertile in comparison with those of ordinary long- styled plants when self-fertilised. I was thus led to examine the plants in several small collections, and the result showed that the equal-styled variety was not rare.
TABLE 5.31. Primula Sinensis. Preponderance of long-styled over the short-styled form.
Column 1: Name of owner or place. Column 2: Long-styled form. Column 3: Short-styled form. Column 4: equal-styled variety.
Mr. Horwood : 0 : 0 : 17. Mr. Duck : 20 : 0 : 9. Baston : 30 : 18 : 15. Chichester : 12 : 9 : 2. Holwood : 42 : 12 : 0. High Elms : 16 : 0 : 0. Westerham : 1 : 5 : 0. My own plants from purchased seeds : 13 : 7 : 0. Total : 134 : 51 : 43.