144 BRITISH PLANTS 



Symbiotic Insects. — ^We have already drawn attention 

 to the fact that certain plants make use of resident 

 insects as a protection against other insects (myrmeco- 

 phytes, p. 133). If the under surface of the leaves of the 

 lime and beech be examined, small nests of hairs will be 

 found in the angles between the veins. In these tiny 

 grottoes swarm multitudes of minute insects which may 

 possibly perform a service to the plants upon which they 

 Uve by devouring the spores and germs of disease. 



