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Show ' 146 HETEROSTYLED TRIMORPHIC PLANTS. CHAP. IV. are a little upturned, so that they. may ?e br~1shed by the lower hairy surfaces of the Insects bodies. The shortest stamens which lie enclosed within the calyx of the long- and mid-styled for~s can be touched only by the proboscis and narrow chin of a bee ; hence they have their ends more upturned, and they are graduated in length, so as to fall into a nan~ow file, sure to be raked by the thin intruding proboscis. The anthers of the longer stamens stand laterally farther apart and are more nearly on the same level, for t~ey h~ ve to brush . against the whole breadth of the Insects body. In very many other flowers the pistil, or the stamens, or both are rectangularly .bent to one side of the flower. This' bending may be ·permanent, as with Lythrum and many others, or may be· effected,. as in Dictamnus framinella and others, by a temporary movement, which occurs in the case of the stamens · when the anthers dehisce, and in the case of the pistil when the stigma is mature ; but these two movements do not always take place simultaneously in the same flower. Now I have found no exception to the rule, that when the stamens and pistil are bent, they bend to that side of the flower which secretes nectar, even though there be a rudimentary necta~y of large si~e on the opposite side, as in some species of Oorydahs. When nectar is secreted on all sides, they bend to that side where the structure of the . flower allows. t~e easiest access to it, as in Lythrum, various PapihonaceEe, and others. The rule consequently is, that when the pistils and stamens are curved or bent, the stigma and anthers are thus .b:tou.ght into the pathway leading to the nec~ary. . f.'~ere are a few case; which seem to be exceptions to this rul~, but they ar not so in truth; for instance, in the Gloriosa lily,·t~~ stigma of the grotesque and rectangularly bent P18 1 CHAP. IV. LYTHRUM SALIOARIA. 147 is brought, not into any pathway from the out ide towards the nectar-secreting recesses of the flower, but into the circular route which insects follow in procee ling from one nectary to the other. In Scrophularia aquatica the pistil is bent downwards from the mouth of the corolla, but it thus strikes the pollen-dusted breast of the wasps which habitually visit these illscented flowers. In all these cases we see the supr me dominating power of insects on the structure of flowers, especially of those which have irregular corollas . Flowers which are fertilised by the wind must of course be excepted; but I do not know of a single instance of an irregular flower which is thus fertilis d. Another point deserves notice. In each of the thre forms two sets of stamens correspond in length with the pistils in the other two forms. When be s suck the flowers, the anthers of the longest stamens, bearin~ the green pollen, are rubbed against the abdomen and the inner sides of the hind legs, as is likewise the stigma of the long-styled form. The anthers of the mid-length stamens and the stigma of the mid-styled form ar rubbed against the under side of the thorax and b - tween the front pair of legs. And, lastly, the anthers of the shortest stamens and the stigma of the shortstyled form are rubbed against the proboscis and chin; for the bees in sucking the flowers insert only the front part of their heads into the flower. On catching bee , I observed much green pollen on the inner sides of th hind legs and on the abdomen, and much yellow pollen on the under side of the thorax. Ther Wtt also pollen on the chin, and, it may be presum d, on the proboscis, but this was difficult to observe. I had, however, independent proof that pollen is carried on the proboscis ; for a small branch of a protected shortstyled plant (which produced spontaneously only two L 2 |