134 BEITISH PLANTS 



service the plant provides the resident ants not only with 

 shelter, but with all the food they require. 



We have no conclusive example of myrmecophily in 

 the British flora. The presence, however, of extra-floral 

 nectaries suggests in some cases relations with ants. Ants 

 on their way to plunder the flower are side-tracked by 

 these offers of food. In the same way the honey- dew on 

 the leaves of the lime and maple may serve to attract 

 ants. What service the ants perform in return for this 

 food is not clear ; they may possibly destroy the eggs of 

 injurious insects. 



There is no line of demarcation between the symbiosis 

 which benefits and the parasite that destroys, or the 

 insects that merely rob. All alike must live, and even in 

 symbiosis the friend may become a foe, and assume the 

 privileges of a master instead of the rights of a partner. 

 In many a case of symbiosis one of the partners is a 

 parasite in disguise. 



