Most of the anthers on one plant were contabescent. Seventeen flowers on the grandchildren were illegitimately fertilised with pollen taken from other seedlings of the same lot, and produced fourteen capsules, containing on an average 29.2 seeds; but they ought to have contained about 35 seeds. Fifteen flowers legitimately fertilised with pollen from an illegitimate short-styled plant (belonging to the lot next to be described) produced fourteen capsules, containing an average of 46 seeds; they ought to have contained at least 50 seeds. Hence these grandchildren of illegitimate descent appear to have lost, though only in a very slight degree, their full fertility.

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.

SUMMARY ON THE TRANSMISSION OF FORM, CONSTITUTION, AND FERTILITY OF THE ILLEGITIMATE OFFSPRING OF Primula Sinensis.

Charles Darwin

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