Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/61

. I. with their much stronger ones, could penetrate with ease the soft inner membrane of the nectaries of the above-named Orchids. Dr. H. Müller is also convinced that insects puncture the thickened bases of the standard petals of the Laburnum, and perhaps the petals of some other flowers, so as to obtain the included fluid.

The various kinds of bees which I saw visiting the flowers of Orchis morio remained for some time with their proboscides inserted into the dry nectaries, and I distinctly saw this organ in constant movement. I observed the same fact with Empis in the case of O. maculata; and on afterwards opening several of the nectaries, I occasionally detected minute brown specks, due as I believe to the punctures made some time before by these flies. Dr. H. Müller, who has often watched bees at work on several species of Orchis, the nectaries of which do not contain any free nectar, fully accepts my view. On the other hand, Delpino still maintains that Sprengel is right, and that insects are continually deceived by the presence of a nectary, though this contains no nectar. His belief is founded chiefly on a statement by Sprengel that insects soon find out that it is of no use to visit the nectaries of these orchids, as shown by their fertilising only the