PLANTS THAT KEEP AN ARMY 53 



The vetches are of the class of plants which make 

 a practice of bribing creeping and crawling insects 

 to leave their honey untouched because they know 

 that they must be fertilised by flying insects. In 

 addition to the sweets stored in their blossoms, the 

 plants have tiny glands, filled with sugar, located 

 below the flower; and this is offered as a bribe to 

 the unwelcome, crawling guest. But this is not all 

 the protection the plant has: there are numerous 

 sharp-pointed hairs protecting the passage-way to 

 the flowers. As a result of these precautions, the 

 ant usually eats the proffered sweets and leaves the 

 nectar in the blossoms for more favoured winged 

 insects, who pay for their honey by distributing the 

 pollen of the plant. 



Many plants make servants, or allies, of the ants ; 

 and others keep such a vast number of protectors 

 that they may be termed their "standing armies." 



A good example of plants that keep servants and 

 live stock is one of the ferns, Polypodium nee- 

 tariferum. This fern receives ants as most wel- 

 come guests and allies; it furnishes them with a 

 good home and food in the form of honey; in re- 

 turn they protect the fern from various forms of 

 insects and leaf -cutting ants, thus maintaining mu- 

 tually satisfactory arrangements. 



Not the least singular instance of intelligence dis- 



