Chap. IX. CONCLUDING REMAEIiS. 287 



uses of the variously shaped and placed petals and 

 sepals have been given. So again, the importance of 

 as light difference in the shape of the caudicle of the 

 poUinium of the Bee Ophrys, compared with that of 

 the other species of the same genus, has likewise been 

 referred to ; to this might be added the doubly-bent 

 caudicle of the Fly Ophrys. Indeed, the important 

 relation of the length and shape of the caudicle, with 

 reference to the position of the stigma, might be cited 

 throughout many whole tribes. The solid projecting 

 knob of the anther in Epipactis paJustris, which does 

 not include pollen, liberates the pollen-masses when it 

 is moved by insects. In Cephalanihera grcmdijlora, the 

 upright position of the almost closed flower protects 

 the slightly coherent pillars of pollen from disturb- 

 ance. The length and elasticity of the filament of the 

 anther in certain species of Dendrobium apparently 

 serves for self-fertilisation, if insects fail to transport 

 the pollen-masses. The slight forward incliiiation of 

 the crest of the rostellum in Listera prevents the 

 anther-case being caught as soon as the viscid matter 

 is ejected. The elasticity of the lip of the rostellum 

 in Orchis causes it to spring up again when only one 

 of the pollen-masses has been removed, thus keeping 

 the second viscid disc ready for action, which otherwise- 

 would be wasted. No one who had not studied Orchids 

 would have suspected that these and very many other 

 small details of structure were of the highest importance 

 to each species ; and that consequently, if the species 

 were exposed to new conditions of life, and the structure 

 of the several parts varied ever so little, the smallest 

 details of structure might readily be acquired through 

 natural selection. These cases afford a good lesson of 

 caution with respect to the importance of apparently 

 trifling particulars of structure in other organic beings. 



