Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/72

52 Ophrys, and is much more rigid; the upper part is naturally curved forward; the lower part undergoes the usual movement of depression, when the pollinia are removed from their cells. The pollen-masses never fall spontaneously out of their cells. This plant, therefore, differs in every important respect from O. apifera, and seems to be much more closely allied to O. aranifera.

Ophrys scolopax of Cavanilles.—This form inhabits the north of Italy and the south of France. Mr. Moggridge says that at Mentone it never shows any tendency to fertilise itself, whilst at Cannes the pollen-masses naturally fall out of their cells and strike the stigma. He adds: "This material difference between the two is accomplished by a very slight bend in the anther-ceils, which are prolonged into a beak of variable length, in the case of the self-fertilising blossoms."

Ophrys apifera.—The Bee Ophrys differs widely from the great majority of Orchids in being excellently constructed for fertilising itself. The two pouch-formed rostella, the viscid discs, and the position of the stigma, are nearly the same as in the other species of Ophrys; but the distance of the two pouches from each other, and the shape of the pollen-masses are somewhat variable. The caudicles of the pollinia are remarkably long, thin, and flexible, instead of being, as in all the other Ophreæ seen by me, rigid enough to stand upright. They are necessarily curved forward at their upper ends, owing to the shape of the anther-cells; and the pear-shaped pollen-masses lie embedded high above and directly over the