VEGETABLE PHYSIOLOGY. 73 



some trees, such as the fir, that never send out any shoots after 

 the oneration of felling. 



8. Destruction of Buds. It has been already shown that the 

 buds which expand in the spring are generated in the preceding 

 summer, and augmented and prepared for developement in the 

 intervening winter. But if the buds are destroyed in the course 

 of the winter, or in the early part of the spring, many plants will 

 again generate new buds that will develop their parts as the 

 others would have done, except that they never contain blossom 

 or fruit ; probably because the fruit bud requires more time to 

 develop its parts, or a peculiar and higher degree of elaboration ; 

 and that this hasty production is only the effect of a great effort 

 of the vital principle for the preservation of the individual, and 

 one of those wonderful resources to which nature always knows 

 how to resort when the vital principle is in danger. 



9. Destruction of Leaves. Sometimes the leaves of a tree 

 are destroyed partially or totally as soon as they are protruded 

 from the bud, whether by the depredations of caterpillars or other 

 insects, or by the browsing of cattle. But if the injury is done 

 early in the spring, new leaves will be again protruded with 

 subsequent shoots. Some trees will bear to be stripped of their 

 leaves even more than once in a season, as is the case with the 

 mulberry tree, which is cultivated for the purpose of feeding silk 

 worms. But if it is stripped more than once in the season it 

 requires now and then a year's rest. 



10. Destruction of Bark. The decortication of a tree, or 

 the stripping it of its bark, may be 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, 

 without leaving any scar. But if the epidermis of the petal, leaf 

 or fruit, is destroyed, it is not again regenerated, 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 

 epidermis, particularly if the wound is not protected from the 

 action of the air. And if the decortication reaches to the wood, 

 then the wound will not heal in the foregoing manner at all. If 

 the decortication is total, the tree dies. Of sixty trees which 



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