LETTING THE BEES DO THEIR WORK 



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 horn-like 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 

 together 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 

 deposit of their important burden; and in this 

 case the arrangement is such that a portion of the 

 fructifying powder is deposited on each of the two 

 pistils with which this species is equipped. 

 THE SENSES OF INSECTS 



It is needless to multiply instances of the 

 wonderful adaptations of form through which 

 the various species of plants have made sure that 

 the insects for which nectar is provided shall 

 carry out their part of the bargain. 



Some flowers have long tubes which only the 

 coiled proboscis of a moth or the slender bill of 



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