402 



BRITISH FLOWERING PLANTS 



causes it to rupture transversely, and thus to expose the 

 two viscid balls {d d). Now suppose an insect visiting 

 ■t-iis flower : it alights on the lip {I), and pushing its 

 pioboscis down the spur it can hardly fail to bring 



Fig. 330. Ord.i^^g mascwla. Side view of flower 

 witli petals and sepals cut off except the 

 lip, or wnioij ^jig jjgar half is cut away, as 

 well as the ii,pper portion of the near side of 

 the nectary. 



a, the pair of anther cells ; l, labellum ; -rt, nectary ; r, rostellum ; 



Fig. 331. — Front view of flower, 

 with all sepals and petals re- 

 moved except the lip. 



it, stigma. 



the base of the proboscis into contact with the two 



viscid disks,. ^y^riiic;^. at once adhere to it, so that when 



the insect' withdraws, it carries away the two pollen 



masses. It is easy to imitate this 



with a piece of grass, and to carry 



away on it the two pollen masses 



'and their stalks. If, however, the pol- 



^linium retained this erect position when 



'the insect came to the next flower, it 



y^puld simply be pushed into or against 



1*^3 old position. Instead, however, of 



J^si-naining upright, the poUinia, by the 



Fig. 332 -The two ,^°°- "v^^^ction of the minute disk of mem- 



poiiinia. d, viscid oran\e to which they are attached, 



rostellum ™^'"'"' g^adrially tum downwards and for- 



ward^ and thus when the insect sucks 



the next flower, the thvick end of the club exactly strikes 



the stigmatic surfaces \(st, st). The poUinium or pollen 



