Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/225

. VII. have resembled the males of C. saccatum and callosum, for as we have just seen, it is to these two plants that Myanthus presents so many striking resemblances.

Lastly I may be permitted to add that Dr. Crüger, after having carefully observed these three forms in Trinidad, fully admits the truth of my conclusion that Catasetum tridendatum is the male and Monachanthus viridis the female of the same species. He further confirms my prediction that insects are attracted to the flowers for the sake of gnawing the labellum, and that they carry the pollen-masses from the male to the female plant. He says "the male flower emits a peculiar smell about twenty-four hours after opening, and the antennæ assume their greatest irritability at the same time. A large humble-bee, noisy and quarrelsome, is now attracted to the flowers by the smell, and a great number of them may be seen every morning for a few hours disputing with each other for a place in the interior of the labellum, for the purpose of gnawing off the cellular tissue on the side opposite to the column, so that they turn their backs to the latter. As soon as they touch the upper antenna of the male flower, the pollen-mass, with its disc and gland, is fixed on their back, and they are often seen flying about with this peculiar-looking ornament on them. I have never seen it attached except to the very middle of the