THE PLANTEK's GUIDE. 



159 



dent on certain external conditions ; and that, when those 

 conditions are imperfectly supplied, this development can- 

 not take place. It has been further observed, that the 

 most perfect development in all cases appears manifest 

 where the protecting properties are most fully displayed. 

 If these things be true, it will follow that to prepare trees 

 for removal only means to allow nature, if I may so 

 speak, to do her own work : and that we shall always 

 best accomplish by clearing away those accidental 

 obstacles and mechanical impediments which are some- 

 times thrown in her way, as they obstruct and misdirect 

 the simple but efficient methods which she employs 

 towards the accomplishment of one of the most beautiful 

 as well as complicated of her processes. The difficulty 

 lies in administering to nature discreetly ; neither 

 officiously directing her on the one hand, nor rudely con- 

 trolling her on the other. 



The main obstacle or impediment to the acquisition of 

 the protecting properties in trees is shelter and closeness, 

 or the want of a sufficient action of the atmosphere 

 around them. Vegetable, like animal life, is dependent 

 for its existence on the external conditions of food, air, 

 water, and heat, while light is a condition more peculiar 

 to plants. Where trees, as in unthinned plantations, 

 press too closely on one another, the range which the 

 roots require for their food is circumscribed. Wind being 

 in a great degree excluded, and evaporation prevented, 

 heat is by consequence generated in an undue degree. 

 In the same way, light is nearly shut out from such 

 plantations, except from the top, and a disproportioned 

 elongation of the stem is occasioned by the efforts which 

 each individual makes to gain the light. By these means 

 the bark becomes thinner and more delicate, the roots 

 more scanty, and the spray and branches more open and 



