TREE PLANTING ON STREETS AND HIGHWAYS. 197 



closely-packed soil to exclude the air. They can be placed closely together, and 

 shouid be set in a slanting position with the tops inclined away from the prevailing 

 winds. Heeling is also resorted to when nursery stock arrives before preparation 

 has been made for planting. 



This method is favored by some because, when trees are taken up in the spring 

 the '' callus " which forms on the mutilated roots will not put out its white, hairy- 

 like fibres in time to furnish sap for the early buds that are dependent on them ; 

 but when taken up in the fall and heeled in, the callus forms during the winter, and 

 is ready with its new fibrous growth to furnish nourishment as soon as transplanted. 



Pratiing. 



As trees grow larger and older they require pruning occasionally to remove 

 dead limbs, to improve their shape, and, in the case of very old trees, to restore 

 them to vigor. This work should not be entrusted to ignorant, inexperienced 

 persons, as is too often the case. Men of this class frequent our cities, and solicit 

 employment as tree pruners. With glib tongues they describe the defects, real 

 or otherwise, in street or lawn trees, and obtain permission to do some work. 

 As a result, beautiful specimens have been disfigured or irremediably injured. 

 Whenever any extensive pruning becomes necessary proper means should be taken 

 to secure the services of skilful, experienced men who have testimonials or 

 recommendations signed by some competent authority in such matters. 



Some of our best shade trees can be improved in appearance occasionally by 

 trimming or cutting back in order to correct irregularities, or to attain some 

 form better adapted to the situation. Such work can be done without injury 

 to the trees ; but it can be undertaken safely only by a skilful, professional tree 

 pruner. 



When a tree becomes " stag headed " by dying at the top the dead limbs thus 

 exposed should be cut off, and the rest of the tree trimmed somewhat to correct the 

 irregularity in its general outline. Old trees that have become bare and unsightly 

 may often be restored to temporary vigor and clothed with foliage by severe prun- 

 ing; but any extensive trimming of this kind is justifiable only when it is neces- 

 sary to prolong the life of a tree which otherwise would soon die. Some species, 

 Hard Maple for instance, along a walk or driveway can be made more serviceable 

 under certain conditions by increasing their height, which is accomplished by 

 cutting off a few of their lower limbs, f But this operation requires careful, intelli- 

 gent work, and should not be resorted to unless there are special reasons for it. 



