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trees are planted, they require a certain portion of organ- 

 izable matter for their support, and as trees increase in size 

 they require more nourishment ; but at the time they require 

 more, men give or allow them less ; and if all remain on the 

 ground as planted, how is it possible that they should ever 

 become timber trees ? how can any animal get fat without 

 plenty of food ? 



In Professor Henslow's opinion, the power of ramification 

 inherent in the roots is the most beautiful instance of design 

 that we meet with in so fertile a field as that of vegetation ; 

 it compensates for their want of power of moving from place 

 to place; but, when trees are crowded, this power is very 

 much circumscribed. The principal roots may be considered 

 as the great arteries which convey the sap to the stem, and 

 the small fibres as indispensable auxiliaries, with their thou- 

 sand mouths running in every direction, sucking in all the 

 fluids which present themselves, and conveying them to the 

 principal roots, whence they are passed into the stem. 



Planting and subsequent management of trees are totally 

 distinct, though both are essential to ultimate success. Many 

 gentlemen there are, I firmly believe, who think there is 

 nothing more to be done after the tree is put into the ground; 

 and the rewards given by the Society of Arts in the Adelphi 

 have been premiums given for the greater number of trees 

 planted, without any regard to their after cultivation. 



Another and main consideration is the leaf. If trees stand 

 too near to each other, they cannot throw out leaves suflScient 

 to obtain support from the air ; the tops only being exposed 

 to the light, are drawn up, and the trees, if not thinned out, 

 become too tall to be supported by the strength of their bole. 



During the day, and while plants are exposed to the influ- 

 ence of the light, carbonic acid is absorbed by them, and 

 decomposed, the carbon alone being retained in their struc- 

 ture while the oxygen is given off. During the night, and 



