THE WIND AS CAKRlER. 



139 



be mistaken for petals by all but botanists. One 

 way in which such a substitution often happens 

 is shown us by the 



great burnet, which ^^ -^ "^ 



is a close relation of 

 thesalad-burnet. This 

 plant, after having 

 acquired the habit of 

 wind-fertilisation, has 

 taken again at last 

 to insect marriage. 

 Having lost its petals, 

 however, it can't 

 3asily redevelop them ; 

 30 it has had instead 

 to make its calyx 

 purple. The plant as 

 a whole closely re- 

 sembles the salad- 

 burnet ; but the 

 flowers are rather 

 different ; the stamens 

 no longer hang out 

 of the calyx ; the 

 calyx cup is more 

 tubular ; and the 

 stigma is shortened 

 to a little sticky knob, 

 instead of being 

 divided into feathery 

 fringes. These dif- 

 ferences are all very characteristic of the con- 

 trast between wind and insect-fertilisation. 

 The common nettle supplies us with an excel- 



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