THE planter's GUIDE. 



89 



usually tliiu, the former often smooth and glossy. The 

 descending vessels, by consequence, as they lie under it, 

 never fail to suffer severely on being exposed to a cold 

 atmosphere. It is greatly on this account, as well as from 

 scantiness of roots and lateral boughs, that plantations 

 sustain such extensive injury on being suddenly thinned. 

 AVhere that operation is performed in a gradual manner, 

 it gives time for nature to prepare the trees for the 

 change by strengthening the coat of bark, and like- 

 wise by multiplying the roots and thickening the spray 

 and branches ; and thus the proper vessels are prevented 

 from being chilled by untimely exposure. The fact, though 

 universally known, is never referred to the true cause by 

 common observers. 



These considerations furnish ample ground to admire 

 the wise provision of nature in bestowing a much thicker, 

 coarser, and more indurated covering of bark upon all 

 trees in open exposures ; for in vain might they possess 

 every other property, if the sap-vessels were not suffici- 

 ently protected and enabled to do their ofl&ce. Were that 

 to happen through the tliinness of the bark, there cannot 

 be a doubt but that the plants would become stunted and 

 si('kly, and both branches and spray would suffer injury 

 in consequence, as we see happen to the generality of 

 transplanted trees which do not possess this protecting 

 property. From all which it appears, that the health 

 and protection of the proper vessels, by means of a due 

 thickness and indm^ation of bark, is an indispensable pre- 

 requisite in all subjects meant for removal, and that it is 

 deserving of the rank here assigned to it. 



Secon^dly. — Girth and stoutness of stem. Next to 

 thickness of bark, the fitness of the tree for removal greatly 

 depends on this property. The stem or trunk of woody 

 plants is classed by phytologists among the conservative 



