226 THE ORCHIDACE^ OF THE 



from this circumstance, the caudicle is not capable of that move- 

 ment of depression characteristic of all the species of Orchis, for 

 this movement is always excited when the upper membrane of the 

 disc is first exposed to the air. The ball of viscid matter is 

 bathed in fluid within the pouch formed by the lower half of the 

 rostellum, and this is necessary, as the viscid matter rapidly sets 

 hard in the air. The pouch is not elastic, and does not spring up 

 when the pollinium is removed. Such elasticity would have been 

 of no use, as there is here a separate pouch for each viscid disc, 

 whereas in Orc/iis, after one pollinium has been removed, the 

 other has to be kept covered up and ready for action. Hence it 

 would appear as if Nature was so economical as to save even 

 superfluous elasticity. The pollinia. as ]\Ir. Darwin observes, 

 cannot be jarred out of the anther-cells by violence. This 

 eminent naturalist remarks, " That insects of some kind visit these 

 flowers, though not frequently, and remove the pollinia, is certain. 

 Twice I have found abundant i)ollen on the stigmas of flowers, in 

 which both their own pollinia were still in their cells, and no 

 doubt had I looked oftener I should have oftener observed this 

 fact." My own observation agrees with this. 



Mr. Darwin continues : — '' The elonf^ated labellum forms a 

 good standing-place for insects ; at its base, just beneath the 

 stigma, there is a rather deep depression, representing the nectary 

 in Orchis, but I could never see a trace of nectary, nor have I 

 observed any insects, often as I have watched these inconspicuous 

 and scentless flowers, even approach them. On each side of the 

 base of the labellum there is a shining knob, with an almost 

 metallic lustre, appearing like two drops of fluid ; and if I could in 

 any case believe in Sprengel's sham nectaries, 1 should believe it 

 in this instance. What induces these insects to visit these flowers 

 I can at present only conjecture. The two pointed pouches 

 covering the viscid discs stand not far apart, and project over the 

 stigma ; any object pushed gently right against one of them (in 

 Orchis the push should be directed rather downwards) depresses 

 the pouch, touches and adheres to the viscid ball, and the 

 pollinium is easily removed. The structure of the flower leads me 

 to believe that small insects crawl along the labellum to its base, 

 and tliat in bending their heads downwards or upwards they strike 



