Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/167

. V. it; and as, in this species, the upper surface of the rostellum resolves itself into viscid matter, the caudicles of the pollinia become glued to it without any mechanical aid. The pollinia, though thus attached, cannot, of course, be removed from their anther-cells without the aid of insects. In this species it seems possible (though, from the position of parts, not probable) that an insect might drag the pollinia out and leave them on the stigma of the same flower. In all the other species of Epidendrum which I examined, and in all the above-mentioned genera, it is evident that the viscid matter has to be forced upwards into the lip of the anther by a retreating insect, which would thus necessarily carry the pollinia from one flower to the stigma of another.

Nevertheless, self-fertilisation takes place in some Epidendreæ. Dr. Crüger says that "we have in Trinidad three plants belonging to this family (a Schomburgkia, Cattleya, and Epidendron) which rarely open their flowers, and they are invariably found to be impregnated when they do open them. In these cases it is easily seen that the pollen-masses have been acted on by the stigmatic fluid, and that the pollen-tubes descend from the pollen-masses in situ down into the ovarian canal." Mr. Anderson, a skilful cultivator of Orchids in Scotland, also states that several of his Epidendreæ fertilise themselves spontaneously. In the case of Cattleya crispa, the flowers sometimes do not expand properly; nevertheless they produce capsules, one of which he sent to me. It contained an abundance of seeds, but on examination I found that