CHAPTER XV. 



THE ORIGIN OF FLORAL APPEXDAGES. 



Epidermal Trichomes, etc. — While all conspicuous flowers 

 inyite insects of some sort or another to visit them, which, by 

 so doing, pollinate their stigmas, it is an important thing to 

 be able to exclude those which w^ould rifle the flower of its 

 treasures and yet not transfer the pollen from one flower to 

 another. Dr. Kerner, in his interesting work entitled Floivers 

 and their Unbidden Guests, has described and figured a large 

 number of instances of the forms of floivers in which he 

 detects various processes, some of which produce sticky 

 secretions, others occurring as hairy " wheels " and " tangles " 

 of wool, etc. ; all of which tend to stop the ingress of ants 

 and other small insects, and thus prevent them from getting 

 at the honey. The question at once arises. How have these 

 processes been caused ? Without attempting to account 

 for all, the theory I offer will, I maintain, be answerable 

 for a good many, especially for several cases of secretive 

 processes and for the hairy obstructions. All these I would 

 suggest as the immediate results of the irritations set up by 

 insects ; so that, as a consequence, they occur just and only 

 where they are wanted ; so that, while they form no hindrance 

 to the larger and stronger insects which have presumably 

 caused them to be developed, they, however, may effectually 

 prevent the smaller ones from ertering. 

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