196 DISTRIBUTION. [CH. XIV 



conveyed from tree to tree by birds. The wild rose, 

 the elder, and the hawthorn are often found in England 

 growing on ruins or other places inaccessible except to 

 birds ; in southern Europe, too, the fig is said to spring up 

 in crannies of steep rocks, or the faces of precipices, where 

 doubtless the seeds have been left by birds. 



