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Show 94 HETEROSTYLED Dil\iORPHIC PLANTS. CHAP. III. one sex to the other, or from hermaphrodite to hermaphrodite, we can recognise structure as manifest! y adapted to its action as to that of insects w~en .these ~re the carriers. vVe see adaptation to the Wlnd ln the Illcoherence of the pollen,-in the inordinate quantity produced (as in the Ooniferre, Spinage, &c.),-in the dangling anthers well :fitte~ to shake out. the pol~en,in the absence or small s1ze of the penanth,-1n the protrusion of the stigmas at the period of fertilis~tion, -in the flowers being produced before they are h1c.lden by the leaves,-and in the stigmas being downy or plumose (as in the Graminere, Docks, &c.), so as to secure the chance-blown grains. In plants which are fertilised by the wind. the flowers <lo not secrete nectar, their pollen is too incoherent to be easily collected by insects, they have not brig h t-colourecl corollas to serve as guides, and they are not, as far as I have seen, visited by insects. When insects are the agents of fertilisation (and this is incomparably the more frequent case with hermaphrodite plants), the wind plays no part, but we see an endless nu1nber of adaptations to ensure the safe transport of the pollen by the living workers. These adaptations are most easily recognised in irregular flowers; but they are present in regular flowers, of which those of Linum offer a good instance, as I will now endeavour to show. I have already alluded to the rotation of each separate stigma in the long-styled form of Linum perenne. In both forms of the other heterosty led species and in the homostyled species of Linum which I have seen, the stigmatic surfaces face the centre of the flower, with the furrowed backs of the stigmas, to which the styles are attached, facing outwards. This is the case with the stigmas of the long-styled flowers of L. perenne whilst in bud. But by the time the flowers CHAP. III. LINUM PERENNE. 95 have expanded, the five stigmas twist round so as to face the circu1uference, owing to the torsion of that part of the style which lies beneath the stigma. I should state that the five stigmas do not always turn round ~ompletely, two or three sometimes facing only obhquely outwards. My observations were made during October; and it is not improbable that earlier in the season the torsion would have been more complete ; for after two or three cold and wet days the movement was very imperfectly performed. The flowers should be exan1ined shortly after their expan~ ion, as. their duration is brief; as soon as they beg1n to w1ther, the styles become spirally twisted all together, the original position of the parts being thus lost. He who will compare the structure of the whole flower in both forn1s of L . . Permute and grandijlorum., and, as I may add, of L. jlavum, will not doubt about the meaning of this torsion of the styles in the one form alone of L. perenne, as well as the meaning of the divergence of the stigmas in the short-sty led form of all three species. It is absolutely necessary as we know, that insects should carry pollen fron1 the flowers of the one form reciprocally to those of the other. Insects are attracted by five drops of nectar, secreted exteriorly at the base of the stamens, so that to reach these drops they must insert their proboscides outside the ring of broad filaments, between them and the petals. In the short-sty led forn1 of the above three species, the stigmas face the axis of the .flower; and had the styles retained their original upright and central position, not only would the stigmas have presented their backs to the insects which sucked the flowers, but their front and fertile surfaces would have been separated from the entering insects |