450 HABITATIONS OF INSECTS. 



and of all sizes from that of a pin's head to that of a 

 walnut. Nor is their situation on the plant less diver- 

 sified. Some are found upon the leaf itself ; others 

 upon the footstalks only ; others upon the roots ; and 

 others upon the buds*. Some of them cause the 

 branches upon which they grow to shoot out into such 

 singular forms, that the plants producing them were 

 esteemed by the old botanists distinct species. Of this 

 kind is the Rose-willow, which old Gerard figures and 

 describes as " not only making a gallant shew, but also 

 yeelding a most cooling aire in the heat of summer, 

 being set up in houses for the decking of the same." 

 This willow is nothing more than one of the common 

 species, whose twigs, in consequence of the deposition 

 of the eg^ of a Cynips in their summits, there shoot out 

 into numerous leaves totally different in shape from 

 the other leaves of the tree, and arranged not much un- 

 like those composing the flower of a rose, adhering to 

 the stem even after the others fall off. Sir James Smith 

 mentions a similar liisus on the Provence willows, which 

 at first he took for a tufted lichen ^. From the same 

 cause the twigs of the common wild rose often shoot 

 out into a beautiful tuft of numerous reddish moss-like 

 fibres wholly dissimilar from the leaves of the plant, 

 deemed by the old naturalists a very valuable medical 

 substance, to which they erroneously gave the name of 

 Bedeguar. None of these variations is accidental or 

 common to several of the tribe, but each peculiar to 

 the galls formed by a single and distinct species of 

 Cj/nips. 

 How the mere insertion of an es,g into the substance 



» Reaum. iii. 417 &c. " Inlrod. to Botani/,3i9. 



