20 OPHKEiE. Chap, I. 



When the lip is depressed, the under and viscid surface 

 of the disc, still remaining in its proper place, is un- 

 covered, and is almost certain to adhere to the touch- 

 ing object. Even a human hair, when pushed into 

 the nectary, is stiff enough to depress the lip or 

 pouch ; and the viscid surface of the saddle adheres 

 to it. If, however, the lip be pushed only slightly, 

 it springs back and recovers the under side of the 

 saddle. 



The perfect adaptation of the parts is well shown by 

 cutting off the end of the nectary and inserting a 

 bi-istle at that end ; consequently in a reversed direc- 

 tion to that in which moths insert their proboscides ; 

 and it will be found that the rostellum may easily be 

 torn or penetrated, but that the saddle is rarely or 

 never caught. When the saddle together with the 

 pollinia is removed on a bristle, the under lip in- 

 stantly curls closely inwards, and leaves the orifice of 

 the nectary more open than it was before ; but whether 

 this is of much service to the moths which frequent 

 the flowers, and consequently to the plant, I wiU not 

 pretend to decide. 



Lastly, the labellum is furnished with two pro- 

 minent ridges (f, figs. A, B), sloping down to the 

 middle and expanding outwards like -the mouth of a 

 decoy; these ridges serve to guide any flexible 

 body, like a fine bristle or hair, into the minute and 

 rounded orifice of the nectary, which, small as it 

 already is, is partly choked up by the rostellum. 

 ^'his contrivance of the guiding ridges may be com- 

 pared to the little instrument sometimes used for 

 guiding a thread into the fine eye of a needle. 



Now let us see how these parts act. Let a moth 

 insert its proboscis (and we shall presently see how 

 frequently the flowers are visited by Lepidoptera) 



