RECEPTION OF FLOWER-SEEKING ANIMALS AT THE FLOWER. 



227 



a stigmatic cavity. Leading into the honey-lined stigmatie cavity is a circular 

 aperture or window, and projecting into the upper margin of this window ia the 

 little pointed, triangular rostellum like the bill of a bird (fig. 258^). When a fly 

 desires to abstract honey from the stigmatic cavity, it stands on the footstool and. 

 puts its head in at the window (fig. 258^). In doing so it touches the extremely 

 sticky tip of the rostellum, which sticks to the top of its head. When satisfied, 

 the fly, in vacating the footstool, drags the two pollinia (pollen-masses), which 



Fig. 258. — Arrangements for the reception of Insects at the entrance to the Flower. 



1 Flower of FhalceTwpsis Sakilleriana. 2 Column of this PRal(Bnopsis ; in front of it Is the little bi-lobed footstool. 3 Pollinia 

 of PhaUeno'psis with heart-shaped gland ; seen from in front. * The same, seen from the side, s a Fly which has 

 alighted upon the footstool is introducing its head into the stigmatic cavity, and simultaneously becoming attached to 

 the gland. ^ Head of the Fly with attached pollinia. ? The same, the stalk of the pollinia has become bent like a 

 swan's neck, s a Fly introducing the pollinia into the stigmatic cavity of another flower ; the column is shown in longi- 

 tudinal section, s Flower of Habenaria hifolia. 10 The same flower visited by Sphinx pinastri; the head of the Sphinx 

 alone is represented, its proboscis has been introduced into the long spur, n Head of Sphinx pinastri with long proboscis. 

 12 Flower of Melianthus major, seen from the side, after removal of some of the petals. 18 Flower of Lonicera Etrusca. 

 2, 3, *, 6, ' slightly enlarged ; the other figures natural size. 



are attached to the rostellum, out of the anther, and goes away with them on its 

 head (258^). It now visits another flower and again alights upon the footstool. 

 Meanwhile the stalk of the two pollinia has bent forwards, like a swan's neck 

 (258^), and as the fly puts its head in at the window the pollinia precede it into 

 the stigmatic cavity and remain sticking to the wall (258 *). 



Eemarkable, also, is the threshold provided for alighting insects on the lower 

 lip of Ophrys cornuta and of the Hemp-nettle (Oaleopsis Tetrahit). The lip of the 



