44 THE OAK. 



and supply their own substance in particular with 

 as much as is required. 



Another gall^ resembling the last in form, being 



LEAF-GALI.S. 



spherical, is found attached to the leaves of the 

 Oak. These vary very much in size, some being 



r 



ARTICHOKE-GALLS. 



as large as a marble ; and each contains a single 

 insect, w^hich, when it arrives at its perfect state, 



