THE STEMS— KINDS AND FORMS; PRUNING 



55 



may not be able to overcome the rigidity of the old bark, 

 and, therefore, do not respond to the treatment. Sometimes 

 the parts witli thinner bark may outgrow in diameter the 

 trunk or the old branches below them. The remedy is 

 to release the tension. This may be done either by soften- 

 ing the bark (by washes of soap or lye), or by separating 

 it. The latter is done by slitting the bark-bound part 

 (in spring), thrusting the point of a knife through the 

 bark to the wood, and then drawing the blade down the 

 entire length of the bark- 

 bound part. The slit is 

 scarcely discernible at first, 

 but it opens with the growth 

 of the tree, filhng up with 

 new tissue beneath. Let the 

 pupil consider the ridges 

 which he now and then finds 

 on trees, and determine 

 whether they have any sig- 

 nificance — whether the tree 

 has ever been released, or in- 

 jured by natural agencies. 



The Tissue covers the 

 Wounds and "heals" them. 

 — This is seen in Fig. 63, in which a ring of tissue rolls out 

 over the wound. This ring of healing tissue forms mo£t 

 rapidly and uniformly when the wound is smooth and regu- 

 lar. Observe the healing on broken and splintered limbs ; 

 also the difference in rapidity of healing between wounds 

 on strong and weak limbs. There is a difference in the 

 rapidity of the heahng process in different kinds of trees. 

 Compare the apple tree and the peach. This tissue may in 



Fig. 63. — Proper Cutting of a 

 Branch. The wound will soon be 

 " healed." 



