the pollinium is shot forth, the large spike-like anther is generally carried with it. If the disc strikes a flat surface like a table, the momentum from the weight of the anther often carries the pollen-bearing end beyond the disc, and the pollinium is thus affixed in a wrong direction for the fertilisation of another flower, supposing it to have been attached to an insect's body. The flight of the pollinium is often rather crooked.[1] But it must not be forgotten that under nature the ejection is caused by the antennæ being touched by a large insect standing on the labellum, which will thus have its head and thorax placed near to the anther. A rounded object thus held is always accurately struck in the middle, and when removed with the pollinium adhering to it, the weight of the anther depresses the hinge of the pollinium; and in this position the anther-case readily drops off, leaving the balls of pollen free, in a proper position for fertilising the female flower. The utility
- ↑ M. Baillon ('Bull. de la Soc. Bot. de France,' tom. i. 1854, p. 285) states that Catasetum luridum ejects its pollinia always in a straight line, and in such a direction that it sticks fast to the bottom of the concavity of the labellum; and he imagines that in this position it fertilises the flower in a manner not clearly explained. In a subsequent paper in the same volume (p. 367) M. Ménière justly disputes M. Baillon's conclusion. He remarks that the anther-case is easily detached, and sometimes naturally detaches itself; the pollinia then swing downwards by the elasticity of the pedicel, the viscid disc still remaining attached to the roof of the stigmatic chamber. M. Ménière hints that, by the subsequent and progressive retraction of the pedicel, the pollen-masses might be carried into the stigmatic chamber. This is not possible in the three species which I have examined, and would be useless. But M. Ménière himself then goes on to show how important insects are for the fertilisation of Orchids; and apparently infers that their agency comes into play with Catasetum, and that this plant does not fertilise itself. Both M. Baillon and M. Ménière correctly describe the curved position in which the elastic pedicel lies before it is set free. Neither of these botanists seems to be aware that the species of Catasetum (at least the five which I have examined) are exclusively male plants.
