BEES DO THEIR WORK 341 



traordinary poUenizing devices of which were 

 first made generally known through the studies 

 of Darwin. A familiar illustration of the 

 methods adopted by this curious tribe is fur- 

 nished by the species known as Orchis mascula, 

 which bears its pollen in small bundles at the 

 end of a slender stalk, at the other end of which 

 is a disc covered with a sticky secretion. An 

 insect cannot secure nectar from the flower 

 without carrying away at least one of these 

 pollen stalks. 



But the most remarkable part of the operation 

 is that, so soon as the insect withdraws from the 

 flower, the pollen stalk, attached hornlike to its 

 head, bends over and curls itself into precisely 

 the position that will inevitably cause it to strike 

 the pistil of the next orchid that the insect visits. 



Another species of orchid, known as Orchis 

 pyramidalis, grows two pollen bundles held to- 

 gether by a sort of collar, with which it deco- 

 rates its insect visitor, clasping it, for example, 

 about the proboscis of a butterfly. Here as in 

 the other case the pollen carriers adjust them- 

 selves in precisely the right position for the de- 

 posit of their important burden; and in this 

 case the arrangement is such that a portion of 

 the fructifjTng powder is deposited on each of 

 the two pistils with which this species is equipped. 



