BEES AS FERTILISERS. 



317 



e 



rostellum, is at first continuous, but, as soon as th 

 flower opens, the slightest touch causes it to rupture 

 transversely, in a sinuous line (lr, C and D) in front 

 of the anther cells. Let us now suppose that a bee 

 (ap, A) alights on the labellum, and advances the 

 head, in order that the tongue may reach the nectary 

 (n), where the sweet liquid must be secured by an 

 abrasion of the delicate lining membrane. The 

 rostellum, irritated by the touch of the insect, im- 

 mediately ruptures its covering skin (if this were 

 entire at the previous moment), and the pushing 

 forward of the head depresses its lip {lr, D), so 

 that the viscid discs (vd), formerly a part of the 

 covering membrane of the rostellum, and the viscid 

 globes (vg), are exposed, the latter infallibly coming 

 into contact with some part of the bee's head. So 

 viscid are these globes that they firmly stick to what- 

 ever they touch ; moreover, they have the property 

 of setting hard in a few seconds. During the time 

 occupied in sucking the nectar, they, in consequence, 

 become firmly attached to the head of the bee, the 

 connected pollen masses still lying in the anther 

 pouches, whence, as we know, they can be readily 

 withdrawn ; this is accomplished as our bee retires 

 carrying a decoration in the form of two upstanding 

 yellowish-green horns {po, D and E, the pollinia of 

 the orchid). Darwin pointed out that all this may be 

 exactly imitated by a well-pointed pencil, or a stiff 

 bristle; and none would regret the little trouble in- 

 volved in growing a few common hardy orchids, in 

 order to have the pleasure of showing the experiment 

 to friends. But how are these pollinia to be made 



