Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/179

. VI. water, after both movements had taken place; and the pedicel then moved into the same position which it had at first assumed through its elasticity; this movement not being in any way affected by the water. When taken out of water the hygrometric movement of depression soon commenced for the second time.

In Rodriguezia secunda there was no hygrometric movement of depression in the pedicel as in the before-mentioned R. suaveolens, but there was a rapid downward movement, due to elasticity, and of this I have seen no other instance; for when the pedicel was put into water it showed no tendency to recover its original position, as occurred in many other cases.

In Phalænopsis grandiflora and amabilis the stigma is shallow and the pedicel of the rostellum long. Some compensating action is therefore requisite, which, differently from that in Maxillaria ornithorhyncha is effected by elasticity. There is no movement of depression; but, when the pollinium is removed, the straight pedicel suddenly curls up in the middle, thus ( ·–&#8994;–- ): the full-stop on the left hand may represent the balls of pollen, and the thick hyphen to the right may be supposed to represent the triangularly shaped disc. The pedicel does not straighten itself when placed in water. The end carrying the balls of pollen is a little raised up after this elastic movement, and the pedicel, with one end raised, and with the middle part upwardly bowed, is well adapted to drop the pollen-masses into the deep stigmatic cavity, over a ledge in front. Fritz Müller informs me of a case in which the shortening of a very long pedicel is effected partly by elasticity and partly by a hygrometric movement. A small Ornithocephalus, growing in South Brazil, has a very long pedicel,