HOW WOUXDS HEAL 



135 



a tendency to die around the margins of wounds even to 

 the extent of loosening the 1)ark. UnquestionalDly such 

 drying is a hindrance to healing. Another point against 

 pruning at that season is that the exposed wood is sure to 

 check more se\-erely than if it is exposed to the air for a 

 shorter time and during a period of the year when the 

 sap flow is more active. 



FIG. 91— SAD EFFECTS OF SLEET STORM 



This Norway maple is one of se\'eral seriouslv injured by a recent storm at 

 State College, Pa. It is doubtful if any pruning or training could have pre\cnled in- 

 jury in this particular case, for the limbs are practically all broken where there were 

 no bad cro;ches or decayed parts. The Norway maple seems to be specially weak. 



But how almut pruning during the growing season ? Is 

 there no objection to it? Yes — a theoretical one, at 

 least. It is claimed that pruning in spring and early 



