. The various contrivances by which orchids are fertilized by insects. Fertilization of plants; Orchids. 62 OFIIIIE-E. Chap. II. finding tlirco (load insects, permanently glued to the discs. Whilst sucking the nectar, which takes two or three minutes, the projecting joint of the femur stands under the large helmet-like viscid disc on either side ; and when the insect retreats, the disc exactly fits on and is glued to the prominent joint, or to the surface of the femur. The movement of depression in the caudicle now takes place, and the mass of pollen-grains then projects just beyond the tibia;
. The various contrivances by which orchids are fertilized by insects. Fertilization of plants; Orchids. 62 OFIIIIE-E. Chap. II. finding tlirco (load insects, permanently glued to the discs. Whilst sucking the nectar, which takes two or three minutes, the projecting joint of the femur stands under the large helmet-like viscid disc on either side ; and when the insect retreats, the disc exactly fits on and is glued to the prominent joint, or to the surface of the femur. The movement of depression in the caudicle now takes place, and the mass of pollen-grains then projects just beyond the tibia; so that the insect, when entering another flower, can hardly fail to ferti- lise the stigma, which is situated directly beneath the disc on either side. Fig. Pkristvlus viridis, op. Frog Orchis. Frout view of flower. a. anther. i n',.'. lateral nectaries, s. stigma. /. labellnm. n. orifice of central nectary. I Peristtjlus viridis.—This plant, which bears the odd Qame of the Frog Orchis, has been placed by many botanists in the genus Habenaria or Platanthera; but as the discs are not naked, it is doubtful whether this. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York, D. Appleton and Co.
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