46'0 Cultivation of Forest Trees. 



forests ; in the former case, its tissue is solidified by the greater 

 quantity of carbon fixed in the system during its growth." 



P. 560. " Mr. Rigg has investigated the connexion between 

 nitrogen and plants. He finds the youngest parts of plants 

 richest in nitrogen. Alburnum he finds to contain more nitrogen 

 than duramen (or heart wood), and fast-growing timber more 

 than slow-growing. He states that his enquiries all tend to 

 prove that nitrogen is evolved during the healthy performance 

 of the functions of plants, and that the atmosphere is the source 

 from which they derive that element. The proportion which it 

 bears to the oxygen given off is influenced by the sun's rays. The 

 difference which he finds in the growth of plants in the shade and 

 sunshine are due in a great measure to the influence of nitrogen." 



Penny Cyclopcedia^ vol. ii. p. 12]. " Trees crowded together in 

 plantations suffer more from the deficiency of carbonic acid and 

 oxygen, both of which are required for respiration, than deficient 

 nutriment by the roots ; a fact of which proprietors and managers 

 of timber plantations are either not aware, or at least they 

 neglect the practice to which it should lead. 



" By the respiration of plants and trees the carbonic acid gas 

 is withdrawn, and an equivalent of oxygen substituted. By the 

 mutual action of the members of the animal and vegetable king:- 

 doms, the balance of the constituent elements of the atmosphere 

 is maintained." 



From the extracts above given it is evident that some advan- 

 tage may be made of science in this neglected art. 



I beg the Society's further attention to a few remarks. Mr. 

 Grigor, who received the Society's prize, states that pruning 

 will not ultimately increase the bulk and weight of timber; 

 whereas Professor Lindley shows that the more succulent or 

 younger parts of plants attract the more nourishment from the 

 atmosphere. In trees pruned by shortening the branches, the 

 whole tree is covered with healthy leaves often three times the 

 size of the adjoining unpruned trees; by which management 

 growths of feet instead of inches will be made. In trees clothed 

 with a healthy foliage by shortening the branches, the ascending 

 sap is so augmented, both in quality and quantity, that it keeps 

 the trees free of mosses. The same takes place in the animal 

 creation ; when unhealthy they are infested with vermin, &c. 



I shall conclude by suggesting to the attention of the Society 

 to follow out the principles inculcated in the remarks and ex- 

 tracts. In the mean time it would be of incalculable advantage, 

 should any member or members place at the disposal of the So- 

 ciety a part of their plantations, containing trees at least six feet 

 in height, to be treated under each system for one, two, or three 

 years. 



The sanction of the Highland and Agricultural Society would 



