94 Flowers and their Unbidden Guests. 



ceneus Pabr.), after alighting on the tips of the corolla, 

 and passing thence by the above-mentioned circuit 

 to the centre of the flower, smear the stigmas with 

 pollen which they had brought from other flowers of 

 the same species.* 



In the genus Tropssolum again there is a " weel " 

 formed by the fringes into which the laterally con- 

 stricted margins of the three lower petals are slit, and 

 over this " weel " all the smaller insects that light on 

 the edge of the petals must climb, if they would get at 

 the nectar. Now suppose a flower, say of Tropoeohim 

 majus, to be without this "weel." In that case an 

 insect, whose body was not more than 2 '5 mm. in thick- 

 ness, would be able after alighting on the three lower 

 petals to creep in between the style and the filaments, 

 and get to the nectariferous spur of the calyx, without 

 touching either stigma or anthers. But if the " weel " 

 be there — consisting as it does of fringed processes 4 

 mm. in length, and not more than 0'5 mm. apart, 

 nay even occasionally intertangling with each other — 

 an insect in climbing over it cannot possibly help 

 coming into due contact with stigma and anthers, 

 seeing that these lie immediately behind it. Similar 

 weels and trellises made out of fringes are to be 



' These little beetles tried, indeed, to get at the nectar in the 

 bottom of the bell, but, owing to the arch which protects it (which 

 will be described in the next section), without success. At last 

 they returned over the style, and contented themselves with the 

 poUen with which this was coated. 



