Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/182

162 the long nectary close beneath the rostellum. The labellum is studded with singular, wartlike, globular excrescences.

If a thick needle be inserted into the mouth of the nectary (fig. A), and then withdrawn, the viscid disc is removed, bearing with it the elegant fan of radiating pollen-masses. These undergo no change in position. But if the needle be now inserted into the nectary of another flower, the ends of the pollen-masses necessarily hit the upper and laterally sloping sides of the rostellum, and, glancing off both ways, strike down into the two lateral pit-like stigmas. The thin caudicles being easily ruptured, the pollen-masses are left adhering like little darts to the viscid surface of both stigmas (see left-hand stigma in fig. C), and the fertilisation of the flower is completed in a simple manner pleasing to behold.

I should have stated that a narrow transverse rim of stigmatic tissue, beneath the rostellum, connects the two lateral stigmas; and it is probable that some of the middle pollen-masses may be inserted through the notch in the rostellum, so as to adhere to this rim. I am the more inclined to this opinion from having found in the elegant Calanthe vestita the rostellum extending so widely over the two lateral stigmas, that apparently all the pollen-masses must be inserted beneath its surface.

The Angræcum sesquipedale, of which the large six-rayed flowers, like stars formed of snow-white wax, have excited the admiration of travellers in Madagascar, must not be passed over. A green, whip-like nectary of astonishing length hangs down beneath the labellum. In several flowers sent me by Mr. Bateman I found the nectaries eleven and a half inches long, with only the lower inch and a half filled with nectar.