Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/232

212 likewise attractive to insects. In the drawing (fig. 32) the labellum has been forcibly raised a little up, so as to show the depression and the bent filament. In its natural position it may almost be compared to a huge cocked-hat, supported by a footstalk and placed on the head of the column.

The twisting of the column, which I have seen in no other Orchid, causes all the important organs of fructification in the flowers on the left side of the spike to face to the left, and in all those on the right side to face to the right. So that two flowers taken from opposite sides of the same spike and held in the same relative position are seen to be twisted in opposite directions. One single flower, which was crowded by the others, was barely twisted, so that its column faced the labellum. The labellum is also slightly twisted: for instance, in the flower figured, which faced to the left, the midrib of the labellum was first twisted to the right-hand, and then to the left, but in a less degree, and being bent over it pressed on the posterior surface of the crooked summit of the column. The twisting of all the parts of the flower commences in the bud.

The position thus acquired by the several organs is of the highest importance; for if the column and labellum had not been twisted laterally, the pollinia, when shot forth, would have struck the overarching labellum and have then rebounded, as actually occurred with the single abnormal flower having a nearly straight column. If the organs had not been twisted in opposite directions on the opposite sides of the same crowded spike, so as always to face to the outside, there would not have been a clear space for the ejection of the pollinia and their adhesion to insects.

When the flower is mature the three sepals hang