GALLA. GALLS. 87 



(b) German, Bohemian, and French Galls from dif- 

 ferent species of oak, produced by Cynips Kallari, present 

 certain variations. In general they are small circular 

 galls, I to 3 cm. in diameter, light brown in color, generally 

 smooth or with scaly epidermis, rarely warty. 



(c) Various American species of oak give galls, — Quercus 

 alba and bicolor, obtustfolta, virens, lobata, etc. These 

 present a variety of aspects and are used locally in the 

 manufacture of tannic acid. 



