DOG'S MERCURY AND PLANTAIN. 135 



fallen from its high estate and reverted to 

 the less advanced mode of fertilisation by 

 the intermediation of the wind. For some 

 unknown reason or other this species and all 

 its relations have discovered that they get on 

 better by the latter and usually more wasteful 

 plan than by the former and usually more 

 economical one. Hence they have given up 

 producing large bright petals, because they 

 no longer need to attract the eyes of insects ; 

 and they have also given up the manufacture 

 of honey, which under their new circum- 

 stances would be a mere waste of substance 

 to tl^sm, But the dog's mercury still retains 

 a distinct mark of its earlier insect-attracting 

 habits in these three diminutive petals. 

 Others of its relations have lost even these, 

 so that the original floral form is almost 

 completely obscured in their case. The 

 spurges are familiar English roadside ex- 

 amples, and their flowers are so completely 

 degraded that even botanists for a long time 

 mistook their nature and analogies. 



