166 THE OAK 
their eggs in the young tissues of various plants, espe- 
cially oaks and roses. 
Some of the resulting galls are discoid, such as the 
‘oak-spangles’ of our woods; others, again, are spherical, 
such as the common leaf-galls so well known in England, 
and the so-called oak-apple; then there are the ‘ arti- 
choke galls,’ produced by the partial metamorphosis of 
the buds of the oak in which the cynips has laid its 
egg, and many others. 
