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Show 86 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 7 · (3 seeds, but of apparently good seed only 4 · 3 per capsule. At three separate times nea1:ly a h.undrecl flow rs were fertilised illegitimately w1th their ownform pollen, taken from separate plants ; and ~un1erous other flowers were produced, many of which must have received their own pollen. From all these flowers on the seventeen short-styled plants only fifteen capsules were produced, of which only eleven contained any good seed, on an average 4· 2 per capsule. As remarked in the case of the long-sty led plants, some even of these capsules were perhaps the product of a little pollen accidentally fallen from the adjoining flowers of the other form on to the stigmas, or transported by Thrips. Nevertheless the short-styled plants seem to be slightly more fertile with their own pollen than the long-styled, in the proportion of fifteen capsules to three ; nor can this difference be accounted for by the short-styled stigmas being Inore liable to receive their own pollen than the long-styled, for the reverse is the case. The greater self-fertility of the short-styled flowers was likewise shown in 1861 by the plants in my flower-garden, which were left to themselves, and were but sparingly visited by insects. On account of the probability of some of the flowers on the plants of both forms, which were covered under the same net, having been legitimately fertilised in an accidental manner, the relative fertility of the two legitimate and two illegitimate unions cannot be compared with certainty ; but judging from the number of good seeds per capsule, the difference was at least in the ratio of 100 to 7, and probably much greater. Hildebrand tested my results, but only on a single short-styled plant, by fertilising many flowers with their own-form pollen; and these did not produce any CHAP. III. LINUM GRANDIFLORUM. 87 seed. This confirms my suspicion that some of the few capsules produced by the foregoing seventeen short-styled plants were the product of accidental legitimate fertilisation. Other flowers on the same plant were fertilised by Hildebrand with pollen fron1 the long-styled form, and all produced fruit.* The absolute sterility (judging from the experiments of 1861) of the long-styled plants with their own-form pollen led n1e to examine into its apparent cause; and the results are so curious that they are worth giving in detail. The experiments were tried on plants grown in pots and brought successively into the house. First. Pollen from a short-styled plant was placed on the five stigmas of a long-styled flower, and these, after thirty hours, were found deeply penetrated by a multitude of pollen-tubes, far too numerous to be counted; the stigmas had also become discoloured and twisted. I repeated this experilnent on another flower, and in eighteen hours the stigmas were penetrated by a multitude of long pollen-tubes. This is what might have been expected, as the union is a legitimate one. The converse experiment was likewise tried, and pollen from a long-sty led flower was placed on the stigmas of a short-styled flower, and in twentyfour hours the stigmas were discoloured, twisted, and penetrated by numerous pollen-tubes· and this again . ' ' ' Is what might have been expected, as the union was a legitimate one. Secondly. Pollen from a long-styled flower was placed on all five stigmas of a long-styled flower on a separate plant: after nineteen hours the stign1as were dissected, and only a single pollen-grain had emitted a tube, * 'Bot. Zeitung,' Jan. I, 1864, p. 2. |