380 INSECT ARCHITECTURE. 



have several of these galls, which are of various 

 sizes, from that of a filbert to that of a walnut. 



Leafy Gall of Dyer''s Broom, produced hy Cynips genista ? 

 A. gall, natural size; l\. a lealVt magnified. 



A similar but still more beautiful production is 

 found upon one of the commonest of our indigenous 

 willows [Saiix jmrpurea), which takes the name of 

 rose-willow, more probably from the circumstance 

 than from the red colour of its twigs. The older 

 botanists, not being aware of the cause of such ex- 

 crescences, considered the plants so affected as dis- 

 tinct species; and old Gerard, accordingly, figures 

 and describes the rose-willow as " not onlie making 

 a gallant shew, but also yeelding a most cooling aire 

 in the heat of summer, being set up in houses for 

 decking the same." The production in question, 

 however, is nothing more than the effect produced 

 by a species of gall-fly {Cynips salicis) depositing its 

 eggs in the terminal shoot of a twig, and, like the 



