DOG'S MERCURY AND PLANTAIN. 137 



among the mercuries which showed any ten- 

 dency to retain the original coloured petals 

 would soon get weeded out, because insects 

 would eat up all their pollen, thus preventing 

 them from fertilising others ; while those 

 which had green petals would never be 

 noticed and so would be permitted to fertilise 

 one another after their new fashion. In fact, 

 when a blossom which has once depended 

 upon insects for its fertilisation is driven by 

 circumstances to depend upon the wind, it 

 seems to derive a positive advantage from 

 losing all those attractive features by which 

 its ancestors formerly allured the eyes of 

 bees or beetles. 



Here, again, on the roadside is a bit of 

 plantain. Everybody knows its flat rosette 

 of green leaves and its tall spike of grass-like 

 blossom, with long stamens hanging out to 

 catch the breeze. Now plantain is a case 

 exactly analogous to dog's mercury. It is an 

 example of a degraded blossom. Once upon 

 a time it was a sort of distant cousin to the 



