. The various contrivances by which orchids are fertilized by insects. Fertilization of plants; Orchids. 136 Chap. V. other, and afford the only entrance; bnt the presence of these two minute windows (fig. 20) shows how neces- sary it is that insects should visit the flower in this case as in that of most other Orchids. How insects perform the act of fertilisation I have failed to under- stand. At the bottom of the roomy and dark chamber formed by the closed sepals, the minute column stands, and in front of it is the furrowed labellura, \nth a highly flexible hinge, and on each side
. The various contrivances by which orchids are fertilized by insects. Fertilization of plants; Orchids. 136 Chap. V. other, and afford the only entrance; bnt the presence of these two minute windows (fig. 20) shows how neces- sary it is that insects should visit the flower in this case as in that of most other Orchids. How insects perform the act of fertilisation I have failed to under- stand. At the bottom of the roomy and dark chamber formed by the closed sepals, the minute column stands, and in front of it is the furrowed labellura, \nth a highly flexible hinge, and on each side the two upper petals; a little tube being thus formed. When there- fore a minute insect enters, or which is less probable, a larger in- sect inserts its proboscis through either window, it has to find by the sense of touch the inner tube J„ ,, _, in order to reach the nectary at Sr,'/ b the base of the flower. Within ^•i5--" tlis little tube, formed by the M,vsDEVALux Fi.:.N,:s- column, labellum, and lateral TBATA. petals, a broad and hinged rostel- Thewiiidowontheneaisije ii,m projects at right angles, is shown darkly shaded. i-i -i i j. i which can easily be upturned. It. n6ctnrv> ' Its under surface is viscid, and this viscid matter soon sets hard and dry. The minute caudicles of the poUinia, projecting out of the anther- case, rest on the base of the upper membranous surface of the rostellum. The stigmatic cavity when mature is not very deep. After cutting away the sepals I vainly endeavoured, by pushing a bristle into the tubular flower, to remove the poUiuia, but by the aid of a bent needle, this was effected without much difficulty. The whole structure of the flower seems as if intended to prevent the flower from being easily fertilised; and this proves that we do not understand its structure. Some small insect had entered one of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - color
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1895
