Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/190

170 Acropera. Dr. Crüger says that Gongora maculata "often bears fruit in Trinidad. It is visited, exclusively during the day, as far as I can see, by a splendid bee, probably a Euglossa, but with the tongue nearly twice as long as the body. The tongue passes out behind the abdomen, and is there curved upwards. As these bees only come for biting and gnawing the anterior side of the labellum, the protruding tongue touches or approaches the gland (i. e., viscid disc) at every retrograde movement of the insect. By this it can hardly fail to be loaded sooner or later with the pollen-masses, which are then easily inserted into the stigmatic cleft. I have, however, not as yet observed this fact." I am surprised that Dr. Crüger should speak of the pollen-masses being easily inserted, and I suppose that he must have experimented with dried and shrunken ones. The doubled-up, immensely elongated proboscis, projecting beyond the abdomen, would answer as well as a pointed extremity to the abdomen, which in the case of Acropera I imagine is the instrument for removing the pollen-masses; but I presume that with Gongora it is not the viscid disc, but the broad and free ends of the pollen-masses which are inserted into the stigmatic cavity. As in the case of Acropera, I found it scarcely possible to insert the pollen-masses of Gongora into the stigma; but some which were removed from the anther and left exposed to the sun for nearly five hours, became much shrunk and formed thin sheets; and these could be inserted without much difficulty into the cleft-like entrance of the stigma. The pollinia attached to an insect flying about in the torrid zone would shrink after a time; and the delay thus caused would ensure the