Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/68

48 apart, and project over the stigma; and if any object is gently pushed against one of them, the pouch is depressed and the viscid ball, together with the pollinium adheres to it and is easily removed.

The structure of the flower leads me to believe that small insects (as we shall see in the case of Listera) crawl up the labellum to its base, and that in bending their heads downwards, so as to puncture and suck, or only to examine one of the small shining protuberances, they push against the pouch, and a pollinium is attached to their heads; they then fly to another flower, and there bending down in a similar manner, the attached and doubly-bent pollinium, after the movement of depression, strikes the sticky stigmatic surface, and leaves pollen on it. Under the next species we shall see reason for believing that the natural double curvature of the caudicle compensates for its slight power of movement, compared with that in all the species of Orchis.

That insects visit the flowers of the Fly Ophrys and remove the pollinia, though not effectually or suffi-