150 



VANDE^. 



Chap. VI. 



presented in the diagram) protrude in a not fully- 

 hardened condition through a small slit, and adhere to 

 the back of the rostellum. The upper surface of the 

 rostellum is generally hollowed out for the reception 

 of the pollen-masses ; it is represented as smooth in 

 the diagram, but is really often furnished with crests 



Fig. 23. 

 anther. caudicle 



pollen. 



filament 

 of anther. 



pedicel of 

 rostellum. 



yiscid disc. 



stigma. 



12 3 



Imaginary Section, illustrative of the structure of the column in the 



VANDE.a3;. 



(1 .) The filament, bearing the an- 

 ther with its pollen-masses ; 

 the anther is represented after 

 it has opened along its whole 

 under surface, so that the 

 section shows only the dorsal 

 surface. 



(2.) The upper pistil, with the 



upper part modified into the 



rostellum. 

 (3.) The two lower confluent pistils, 



bearing the two confluent 



stigmas. 



or knobs for the attachment of the two caudicles. 

 The anther afterwards opens more widely along its 

 under surface, and leaves the two pollen-masses un- 

 attached, excepting by their caudicles to the rostellum. 

 During an early period of growth, a remarkable 

 change has been going on in the rostellum : either its 

 extremity or its lower surface becomes excessively 

 viscid (forming the viscid disc), and a line of separa- 



