Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/251

. VIII. orifices, always covered with pollen. I repeated the operation five times, always with the same result. I afterwards cut away the labellum, so as to examine the stigma, and found its whole surface covered with pollen. It should be noticed that an insect in making its escape must first brush past the stigma and afterwards one of the anthers, so that it cannot leave pollen on the stigma, until being already smeared with pollen from one flower it enters another; and thus there will be a good chance of cross-fertilisation between two distinct plants. Delpino with much sagacity foresaw that some insect would be discovered to act in this manner; for he argued that if an insect were to insert its proboscis, as I had supposed, from the outside through one of the small orifices close to one of the anthers, the stigma would be liable to be fertilised by the plant's own pollen: and in this he did not believe, from having confidence in what I have often insisted on—namely, that all the contrivances for fertilisation are arranged so that the stigma shall receive pollen from a distinct flower or plant. But these speculations are now all superfluous; for, owing to the admirable observations of Dr. H. Müller, we know that Cypripedium calceolus in a state of nature is fertilised in the manner just described by bees belonging to five species of Andrena.

Thus the use of all the parts of the flower,—namely, the inflected edges, or the polished inner sides of the labellum,—the two orifices and their position close to the anthers and stigma,—the large size of the medial rudimentary stamen,—are rendered intelligible. An