PLATE 18. 



A branch of Betula alba Linn. 



(One-fourteenth nat. size,) 

 Galled by 



Eriophyes rudis Canest. 



The magnificent specimen illustrated on opposite page is the 

 largest on the birch-tree in Broomham Park. It is mentioned 

 on p. 55. It is an example of the form of growth in which 

 the development takes place from the side of a branch, with a 

 hard, solid, and woody core which also forms part of the branch. 



The two smaller galls beneath it are on separate branches, 

 and are in no way attached to the centre one, nor does the 

 branch which apparently is growing from its base belong to it. 



It measures 8 ft. 6 in. in girth and is 10 ft. from the ground. 

 Its weight must be very great ; the branch is considerably bent 

 by reason of it. 



