HORSE-TAILS 219 



The flies that tore the plant in robbing it of its 

 spores perhaps induced a flow of sugar to the 

 place, though how it could get sugar from the 

 flinty horse-tail is a little of a mystery. That 

 plant thereby became more attractive to nectar- 

 loving insects, and in a thousand years or so an 

 insect arose with the rudiments of a sac wherein 

 to carry honey to its progeny. Among the flowers 

 that offered honey and extra rich pollen, those 

 succeeded best that turned some of the neigh- 

 bouring leaves into a different colour, so that the 

 bee could see from afar, and per contra the bee 

 succeeded best that was not colour-blind, as the 

 flies apparently are. 



Then there began to be bees with the rudiments 

 of a special contrivance on the hind leg to carry 

 off loads of pollen. This robbery the flowers have 

 to put up with, or can only meet by making the 

 pollen hard to brush off from the back or the 

 breast of the bee till it is picked off by the stigma 

 of another plant. The bee has evolved a pollen 

 brush that is almost thorough in its work, but 

 still enough clings to the hairs of the body to 

 achieve the object of the flowers. Few bees are 

 so proficient in cheating the flowers as the hive- 

 bee, wherefore some of the flowers have formed 

 a special alliance with some of the more careless 

 bees by evolving on the one side a tube too long 

 for the hive -bee's tongue, and on the other side a 

 tongue long enough to reach to the bottom of the 

 special tube. A particular bee has been given the 



