Chap. iX. CONCLUDING EEMAEKS. 2S3 



the anther opening a little more widely, becomes 

 specially adapted for the very different purpose of 

 self-fertilisation, throngh the combined aid of the 

 weight of the pollen-mass and the vibration of the 

 flower when moved by the wind. Every gradation 

 between these two states is possible, — of which we have 

 a partial instance in 0. aranifera. 



Again, the elasticity of the pedicel of the pollinium 

 in some Vandete is adapted to free the pollen-masses 

 from their anther-cases ; bnt by a further slight modi- 

 ileation, the elasticity of the pedicel becomes specially 

 adapted to shoot out the pollinium with considerable 

 force so as to strike the body of the visiting insect. 

 The great cavity in the labellum of many Vandea? 

 is gnawed by insects and thus attracts them ; but 

 m Mormodes ignea it is greatly reduced in size, and 

 serves in chief part to keep the labellum in its new 

 position on the summit of the column. From the 

 analogy of many plants we may infer that a long 

 spur-like nectary is primarily adapted to secrete and 

 hold a store of nectar ; but in many Orchids it has so 

 far lost this function, that it contains fluid only in the 

 intercellular spaces. In those Orchids in which the 

 nectary contains both free nectar and fluid in the inter- 

 cellular spaces, we can see how a transition from the 

 one state to the other could be effected, namely, by 

 less and less nectar being secreted from the inner 

 membrane, with more and more retained within the 

 intercellular spaces. Other analogous cases could be 

 given. 



Although an organ may not have been originally 

 formed for some special purpose, if it now serves for 

 this end, we are justitied in saying that it is specially 

 adapted for it. On the same principle, if a man were 

 to make a machine for some special purpose, but were 



