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Show 272 CONCLUDING REMARKS 0IIAP. VI. the 162 illegitimate seedlings in Table 36 were derived in the course of five generations, was itself no doubt derived from the union of a long-sty led and a shortstyled parent; and the 6 short-styled seedlings 1nay be attributed to reversion to their short-styled progenitor. But it is a surprising fact in this case, and in other similar ones, that the number of the offspring which thus reverted was not larger. The fact is rendered still more strange in the particular instance of P. veris, for there was no reversion until four or five generations of long-styled plants had been raised. It may ~e seen in both tables that the long-styled form transmits its form much more faithfully than does the short-styled, when both are fertilised with their own- , form pollen; and why this should be so it is difficult to conjecture, unless it be that the aboriginal parentform of most heterosty led species possessed a pistil which exceeded its own stamens considerably in length.* I will only add that in a state of nature any single plant of a trimorphic species no doubt produces all three forms; and this may be accounted for either by its several flowers being separately fertilised by both the other forms, as Hildebrand supposes; or by pollen from both the other forms being deposited by insects on the stigma of the same flower. Equal-styled varieties.-The tendency of the dimorphic species of Primula to produce equal-styled varieties deserves notice. Oases of this kind have * It may be suspected that this was the case with Primula, judging from the length of the pistil in seveml allied genera (see Mr. J. Scott, 'Journal Linn. Soc. Bot.' vol. viii. 1864, p. 85). Herr Breitenbach found many specimens of Primula elatior growing in a state of nature with some flowers on the same plant long-styled, others short-styled and others equal-styled; and tlle long-styl~.d form greatly preponderated 1.n number; there being 61 of this form to 9 of the short-styled and 15 ofthe equal-styled. CHAP. VI. ON HETEROSTYLED PLANTS. 273 been observed, as shown in the last chapter, in no less than six species, namely, P. veris, vulgaris} Sinensis, auricula, farinosa, and elatior. In the case of P. veris, the stamens resemble in length, position and size of their pollen -grains the stamens of the short-sty led form; whilst the pistil closely resembles that of the long-styled, but as it varies much in length, one proper to the short-sty led form appears to have been elongated and to have assun1ed at the same time the functions of a long-sty led pistil. Oonseq uen tl y the flowers are capable of spontaneous self-fertilisation of a legitimate nature and yield a full comple1nent of seed, or even more than the n urn her prod need by ordinary flowers legitimately fertilised. vVith P. Sinensis, on the other hand, the sta1nens rese1n ble in all respects the shorter ones proper to the long-sty led form, whilst the pistil makes a near approach to that of the shortstyled, but as it varies in length, it would appear as if a long-styled pistil had been reduced in length and modified in function. The flowers in this case as in the last are capable of spontaneous legitimate fertilisation, and are rather more productive than ordinary flowers legitin1ately fertilised. V\7ith P. auric~tla and farinosa the stamens resemble those of the short-styled form in length, but those of the long-styled in the size of their pollen-grains; the pistil also resembles that· of the long-styled, so that although the stamens and pistil are of nearly equal length, and consequently pollen is spontaneously deposited on the stigma, yet the flowers are not legitimately fertilised and yield only a very moderate supply of seed. We thus see, firstly, that equal-styled varieties have originated in various ways, and, secondly, that the combination of the two forn1s in the same flower differs in complete- T |