No. 4.] TREE SURGERY. 451 



This seems at first sight a perfectly easy and simple opera- 

 tion, but after one has cut off some limbs and watched the 

 results for a few years, he may conclude that the task is not 

 so simple as it seems. He may find that the bark dries and 

 that its edges separate from the wood inmiediately about the 

 wound, and also that the cambium dies back for a short dis- 

 tance, thus materially enlarg- 

 ing the space to be covered 

 by the callus. This dying 

 back of the bark is likely to 

 extend more below the wound 

 than on the top and sides. 

 The operator may find that at 

 the end of the first season's 

 growth little if any visible 

 progress in healing over the 

 cut surface has been made, 



the callus formed having been ^1^. 15. _ Branch wou^enlarged by 

 all used in COVerino- the SUr- careless amputation and loosening of bark 

 ^ below. 



face of the wood exposed by 



the dying back and rolling up of the bark. In a year or 

 two more the bark below the wound may have fallen off, 

 leaving the wound enlarged, as in Fig. 15. Such a con- 

 dition of trunk wounds is almost certain to follow amputa- 

 tion, unless the work has been done with the utmost skill 

 and care. 



The injury arises from a separation of the bark from the 

 trunk during the operation, or from a crushing and conse- 

 quent killing of the cambium, both of which are liable to 

 occur in pruning as commonly done. 



If the operator, wishing to use due care to prevent break- 

 ing down the limb, begins his cut from below, saws part 

 way through the limb and then finishes by sawing to meet 

 the cut from above, the limb, when weakened and about to 

 fall, swings downward, thereby bringing the edges of the 

 lower cut together, and, swinging on them as on a pivot, 

 while still held by the unseparated wood, loosens and 

 crushes the cambium at the lower portion of the wound. 

 All loosened or injured cambium dies. The cambium around 



