[page] 320

LINNEAN SOCIETY.  April 3.

ON THE FERTILIZATION OF CERTAIN ORCHIDS. Mr. C. Darwin described some remarkable peculiarities existing in certain orchids, specimens of which were in the possession of the Linnean Society. In the plants belonging to the genus Catasetum, it not unfrequently happens that two, and sometimes three, supposed distinct genera exist on the same spike. Thus the Catasetum tridentatum is inter mixed with the flowers of the Monocanthus viridis and those of the Myanthus barbatus.

LINNEAN SOCIETY. April 3.

[page] 321. Proceedings of Learned Societies.

Mr. Darwin has ascertained that the Catasetum tridentatum is the male form, the flowers bearing pollen masses only; that in the so-called Monocanthus the pollen masses are rudimentary, the inferior ovary being well-developed and twisted, as is usual in orchidaceous plants, and, further, that the so-styled Myanthus barbatus, which is borne on the same plant, is merely the hermaphrodite form.

Mr. Darwin remarked on the very extraordinary mechanism which was necessary to ensure the fertilization of the orchids of the unisexual flowers of the genus Catasetum. The pollen masses are attached to elastic fibres, held down by a membrane, and each is furnished with an adhesive disk. The flowers are furnished with antennae; when these are touched by any object, as an insect, the elastic fibres project out the pollen mass with such force that its adhesive surface adheres to the insect, which, in its search for honey, conveys it to the stigmatic surface of the pistil bearing flower.

Mr. Darwin stated that the position of the excitable surface of the flower varied in the different species, but that the projection of the pollen mass was, in all cases, in such a direction as to cause its attachment to the insect passing over the irritable surface.