I.] 



HEATH. UMBELLIFERS. 



21 



Antirrhinum, which, according to the above given tests 

 ought to be fertilized by insects, is entirely closed. A 

 little consideration, however, will suggest the reply. 

 The Antirrhinum is especially adapted for fertilization by 

 humble bees. The stamens and pistil are so arranged 



FIG. 19. Stamens in their natural 

 position. 



FIG. 20. Stamens when moved 

 by a Bee. 



that smaller species would not effect the object. It is 

 therefore an advantage that they should be excluded, 

 and in fact they are not strong enough to move the 

 spring. The Antirrhinum is, so to speak, a closed box, 

 of which the humble bees alone possess the key. 



The Common Heath (Erica tetralix) offers us a very 

 ingenious arrangement. The flower is in the form of 

 an inverted bell. The pistil represents the clapper, and 

 projects a little beyond the mouth of the bell. The sta- 

 mens are eight in number, and form a circle -round it, 

 the anthers being united by their sides into a continuous 

 ring. Each anther has a lateral hole, but as long as they 

 touch one another, the pollen cannot drop out. Each also 

 sends out a long process, so that the ring of anthers is 

 surrounded by a row of spokes. Now when a bee 

 comes to suck the honey, it first touches the end of the 



