16 BRITISH OAK GALLS. 



(f) Bed. — The same cliromatic gradations are found 

 in this colour, from the most delicate suffusion of 

 pink, as in 7'. crustalis, until a deep crimson or rose- 

 madder is reached, as shown in A. Sieholdi. The most 

 charming example of a median red tint is that of D. 

 scutellariH when at the zenith of its glory. Teras 

 terminalis also often exhibits a wealth of beautiful 

 tints. The brilliant red spots or stripes on the green 

 ground of aS'. baccaru7n accentuate its resemblance to a 

 red-currant berry. The red stripes on Dn/ophanta 

 lonf/iveiitris are worthy of remark. The pretty pink 

 and light red of D. divisa deserves notice ; it is, how- 

 ever, transitory — the l)rown soon asserts itself. The 

 crimson margin of many specimens of Neuroterus 

 IseviuscuJus provides a charming contrast to the 

 greenish-yellow centre. The red and crimson stellate 

 hairlets of N. famipemiis and N. lenficnJaris clothe 

 these galls with rare and most beautiful effect. In 

 addition to these distinctive colours all tints of yellow, 

 also orange, both pale and deep, are to be seen in many 

 galls. White is somewhat unusual, Andricus nodull 

 giving the best example. AphilotJirix Sieholdi is often 

 cream coloured when shielded from the light by loose 

 earth or dead leaves. 



Modifications in Development. 



(a) Due to external influences. — This division in the 

 study of oak galls should receive the attention of the 

 collector and the student, because from the examination 

 of affected specimens some very interesting facts can 

 be deduced, and much of the economy of gall-producing 

 agfents and their allies understood. It is a section 

 which is very near that of " Dissimilarity of shape due 

 to aberrations," yet suflBciently distinctive to be 

 separated. 



Of the modifications in shape and size caused 

 by— 



(a) Overcrowding not much need be said. The 



