On Flowers and Insects. 133 



Probably because the Figwort is one of our few 

 flowers specially visited by wasps, the honey being 

 not pleasing to bees. Wasps, however, unlike 

 bees, generally begin with the upper flowers and 

 pass downwards, and consequently in wasp flowers 

 it is an advantage that the pistil should ripen 

 before the stamens. But though the stamens 

 generally ripen before the pistil, the reverse some- 

 times occurs. Of this a very interesting case is 

 that of the genus Aristolochia. The flower is a 

 long tube, with a narrow opening closed by stiff 

 hairs which point backwards, so that it much re- 

 sembles an ordinary eel-trap. Small flies enter the 

 tube in search of honey, but 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, 

 who carry the pollen to another flower. 



6. Again, in our common Arums, the lords-and- 

 ladies of village lanes, the well-known green leaf 

 incloses a central pillar (fig. 36) ; 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 

 fertilise the stigmas. This, however, is not what 

 occurs. In fact the stigmas come to maturity first, 

 and have lost the possibility of fertilisation before 



