CHAPTER XXII. 



NATURAL WOUNDS. 



Burrows and excavations. Bark-boring Wood-boring 

 Wood fungi Leaf-miners Pith flecks Erosions. 

 Skeleton leaves Irregular erosions Shot holes. 

 Frost cracks Strangulations Spiral grooving. 



Natural wounds are produced in a variety of 

 ways during the life of the plant, and, generally 

 speaking, are easily healed over by the normal 

 process if the area destroyed is not too large, and 

 the parts remaining uninjured are sufficiently pro- 

 vided with foliage, or with supplies of food- 

 materials stored up in the roots, rhizomes, medul- 

 lary rays, etc., to feed a vigorous callus. 



The nature of such wounds and the mode of 

 healing are explained by what we know of arti- 

 ficial wounds, and it only remains to point out 

 that the principal danger of ordinary wounds is 

 not so much the direct traumatic action, because 

 the simpler organisation of the plant does not 

 involve matters connected with shock, loss of 



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