NOTES ON THE VARIOUS SPECIES 253 



The elm, as is a matter of common observa- 

 tion, frequently requires bracing, a result of the 

 manner in which the limbs leave the trunk, or, 

 rather, in which the trunk breaks into limbs. 

 Bolts should of course be used in bracing the 

 spreading limbs of the elm, and never bands or 

 chains. 



HEMLOCK 



The hemlock does not often come under the 

 care of the tree repairer, although the arboricul- 

 turists of the large public parks may occasionally 

 have to prescribe for its treatment. It is subject 

 to a red heart rot (among others) which may be 

 excised if it has not progressed too far. A care- 

 ful survey should precede the attempt. Most 

 fungi probably gain extrance to the trunk through 

 dead branches, which should be removed if of any 

 considerable size, even though such pruning may 

 lessen the picturesqueness of the tree. 



HICKORY 



Besides an average liability to the general run 

 of tree difficulties, the hickory is more than nor- 

 mally subject to becoming bark-bound, on account 

 of the extreme toughness of its outer bark, which 

 in pioneer days was used to make barrels and to 

 roof log cabins. Vertical slits through the outer 

 layers of the cortex are the remedy. 



