482 CASUALTIES OF VEGETABLES. CHAP. XII = 



more than once in the season it requires now 

 and then a year's rest. 



SUBSECTION X. 



Destruction of Bark. The decortication of a 

 tree, or the stripping it of its bark, may be either 

 intentional or accidental, partial or total. If it is 

 partial and affects the epidermis only, then it is again 

 regenerated, as in the case of slight incision, with- 

 out leaving any scar. But if the epidermis of the 

 petal, leaf, or fruit, is destroyed, it is not again re- 

 generated, nor is the wound healed up except by 

 means of a scar. Such is the case also with all 

 decortications that penetrate deeper than the epider- 

 mis, particularly if the wound is not protected from 

 the action of the air. And if the decorticaticn 

 reaches to the wood, then the wound will not heal 

 up in the foregoing manner at all. This Du Hamel 

 proved by means of experiment.* Having stripped 

 a trunk in the spring of a portion of its bark to the 

 extent of a few square inches, he left the decorticated 

 part exposed to the air. In the course of a few days 

 after there appeared issuing from the lip of the 

 wound, as if from between the wood and bark, a ring 

 of new bark, which became broader and more solid 

 during the summer, lessening the area of the origi- 

 nal wound. At the end of the summer it was 

 found that a new layer of wood was formed under 



* Phys. eks Arb. Jiv. iv. chap. iii. 



