THE MAPLE. Ill 



of plants for nutriment, though generally the ob- 

 ject seems to be the formation of a nidus for their 

 young, by the fluid that issues from the wound : 

 but insects do something more than merely punc- 

 turing the parts to force a liquor to exude ; a sim- 

 ple wound will not accomplish the desired object, 

 as the sap not only hardens on the surface, but 

 acquires a particular form and consistence, and even 

 at times enlarges to a separate vegetable matter. 

 The insect that wounds the leaf of the oak, and 

 occasions the formation of the gall-nut, and those 

 which are likewise the cause of the apple rising on 

 the sprays of the same tree, and those flower-like 

 leaves on the buds, have performed very different 

 operations, either by the instrument that inflicted 

 the wound, or by the injection of some fluid to in- 

 fluence the action of the parts. That extraordinary 

 hairy excrescence on the wild rose (cynips rosas), 

 likewise the result of an insect's wounds, resembles 

 no other nidus required for such creatures that we 

 know of; and these red spines on the leaf of the 

 maple are different again from others. It is useless 

 to inquire into causes of which we probably can 

 obtain no certain result, but, judging by the effects 

 produced by different agents, we must conclude, 

 that, as particular birds require and fabricate from 

 age to age very different receptacles for their young, 

 and make choice of dissimilar materials, though 

 each species has the same instruments to effect it, 



