62 



BRITISH OAK GALLS. 



is puslied off by the growth of new wood in the follow- 

 ing spring. 



AYhen denuded of hairs the gall is seen to be longi- 

 tudinally furrowed, but this may sometimes be dis- 

 tinguished Avithout the removal of the hairs, as in 

 inset specimen. (Plate X.) 



When the gall is inhabited by an inquiline it does 

 not attain its usual proportions. 



Internally the gall is divided into nearly equal parts 

 by a septum, the lower portion being hollow, or filled 

 with fibrous reticulations, the upper portion contains 

 the true gall, which is adherent to the inner walls. 



Fig. 5. — Galls caused by Andricus glandidse. a. Yoiinor, showing leaf- 

 scales, and " thatched " appearance, b. Mature, c. Longitudinal 

 section. All x 2^, dele, ad nat. E.C. 



The hirval chamber has a whitish interior and is ovoid 

 in si] ape. 



I am not aware as to the distril)ution of this gall in 

 Britain, wliether it is plentiful or scarce ; possibl}^ it 

 extends over wide areas and w^ould be more frequently 

 observed but for its brief period of growth, rapidity in 

 reaching maturity, and then falling to the ground. 



It has occurred in all the districts in which I have 

 searched, but it appears to be extremely local, and 

 sometimes it will not be found on more than two or 

 three trees in the same wood, and those widely 

 separated from each other. 



According to ni}^ own observations it occurs mostly 

 on oak bushes of eight to ten years' growth, also on 



