Page:On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and on the Good Effects of Intercrossing.djvu/18

 The structure of the flower leads me to believe that small insects (as we shall see in the case of Listera) crawl along the labellum to its base, and that in bending their heads downwards or upwards they strike against one of the pouches; they then fly to another flower with a pollinium attached to their heads, and there bending down to the base of the labellum, the pollinium, owing to its doubly bent caudicle, strikes the sticky stigmatic surface, and leaves pollen on it. Under the next species we shall see good reason to believe that the doubly bent caudicle of the Fly Ophrys serves instead of the usual movement of depression.

That insects do visit the flowers of the Fly Ophrys and remove the pollinia, though not effectually or sufficiently, the following cases show. During several years before 1858 I occasionally examined some flowers, and found that out of 102 only thirteen had one or both pollinia removed. Although at the time I recorded in my notes that most of the flowers were partly withered, I now think that I must have included a good many young flowers, which might perhaps have been subsequently visited; so I prefer trusting to the following observations.

We here see that, out of 207 flowers examined, not half had been visited by insects. Of the eighty-eight flowers visited, thirty-one had only one pollinium removed. As the visits of insects are indispensable to the fertilisation of this Orchid, it is remarkable (as in the case of Orchis fusca) that this Ophrys has not been rendered more attractive to insects. The number of seed-capsules produced is proportionably even less than the number of flowers visited by insects. The year 1861 was extraordinarily favourable to this species in this part of Kent, and I never saw such numbers in flower; accordingly, I marked eleven plants, which bore forty-nine flowers, but these produced only seven capsules. Two of the plants each bore two capsules, and three other plants each bore one, so that no less than six plants did not produce a single capsule! What are we to conclude from these facts? Are the conditions of life unfavourable to this species, though it was so numerous in some places this year as to deserve being called quite common? Could the plant nourish more seed; and would it be of any advantage to it to produce more seed? Why does it produce so many flowers, if a larger number of seed would not be advantageous to it? Something seems to be out of joint in the machinery of its life. We shall presently see what a remarkable contrast another species of this same genus, the Ophrys apifera or Bee Ophrys, presents in producing seed.

Ophrys aranifera, or the Spider Ophrys

I am indebted to Mr. Oxenden for a few spikes of this rare species. The caudicle (Fig. A) rises straight up from the viscid disc, and is then curved or bent forwards in the same manner, but not in so great a degree, as in the last species.

The point of attachment of the caudicle to the membrane of the disc is hidden within the bases of the anther-cells, and is thus kept damp; consequently, as soon as the pollinia are exposed to the air, the usual movement of depression takes place, and the pollinia sweep through an angle of about ninety degrees. By this movement the pollinia (supposing them to have become attached to an insect's head) assume a