CHAPTER XXI. 



ARTIFICIAL WOUNDS. 



The nature of wounds and of healing processes Knife 

 wounds Simple cuts Stripping Cuttings 

 Branch-stumps and pruning Stool-stumps Riiiging 

 Bruises. 



Wounds. All the parts of plants are exposed 

 to the danger of wounds, from mechanical causes 

 such as wind, falling stones or trees, hail, etc., or 

 from the bites of animals such as rabbits, worms, 

 and insects, and although such injuries are rarely 

 in themselves dangerous, they open the way to 

 other agencies water, fungi, etc., which may work 

 great havoc; or the loss of the destroyed or 

 removed tissues is felt in diminished nutrition, 

 restriction of the assimilative area, or in some 

 other way. 



We have seen that living cells die when cut, 

 bruised, or torn ; and that the cells next below in a 

 layer of active tissue are stimulated by the exposure 

 to increased growth and division, and at once pro- 



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