THE ARUM. THE DEADNETTLE. 



17 



from the direction of the hairs it is impossible for 

 them to return. Thus they are imprisoned in the 

 flower until the stamens have ripened and shed their 

 pollen, by which the flies get thoroughly dusted. 

 Then the hairs of the tube shrivel up, thus releasing 

 the prisoners, which carry the pollen to another 

 flower. 



Again, in our common Arums the Lords and Ladies 

 of village children the well-known green leaf incloses 

 a central pillar ; near the base of which 

 are arranged a number of stigmas (st 

 in the accompanying figure), and above 

 them several rows of anthers (a). It 

 might be supposed therefore that the 

 pollen from the anthers would fall on 

 and fertilize the stigmas. This, how- 

 ever, is not what occurs. In fact the 

 stigmas come to maturity first, and 

 have lost the possibility of fertiliza- 

 tion before the pollen is ripe. The 

 pollen must therefore be brought by 

 insects, and this is effected by small FlG 15. -^Diagram- 

 flies, which enter the leaf, either for 

 the sake of honey or of shelter, and 

 which, moreover, when they have once 

 entered the tube, are imprisoned by the fringe of hairs 

 (h). When the anthers ripen, the pollen falls on to 

 the flies, which in their efforts to escape get thoroughly 

 dusted with it. Then the fringe of hairs withers, and 

 the flies, thus set free, soon come out, and ere long- 

 carry the pollen to another plant. 



Now let us return to our White Deadnettle and 



c 



matic section of 

 Aram, h, hairs : 

 a, anthers ; st, 

 stigmas. 



