KELATIVB FORM AND BIZB OF MAIN TREE PARTS. 5 



rapid elongation is also an important factor. For one and the 

 same ag.e, the diameter will, besides being influenced by the soil 

 and the locality, be proportionate to the amount of lateral-grow- 

 ing room afforded to the crown and the roots when the stage of 

 rapid lateral expansion has set in. This generally precedes by a 

 certain interval the close of the stage of rapid elongation. Hence 

 as regards both dimensions we shall obtain the best results by keep- 

 ing the leaf-canopy as close as practicable up to the middle age of 

 the crop, when the upward growth has begun to relax, and there- 

 after by opening it out in proportion to the requirements of the 

 trees. 



(fc). Straightness. — The stem may form (i) a continuous line, 

 or (ii) be contorted or present several angles. In the iirst case it 

 may be straight or curved. If curved, it will be straight in one 

 plane. Such are the crooks and knees of ships, felloes of wheels, 

 &c. Some trees, such as deodar, the firs, Bomhax malaharicum, 

 &c., form a perfectly straight bole, whether they grow isolated or 

 in the midst of a leaf-canopy ; but the rest, which include pines 

 and nearly all broad-leaved species, will grow up straight, only 

 in fully canopied forests, and will even then fall behind deodar and 

 the firs. The soil and the locality, especially depth of soil and the 

 amount of moisture in it, are not without influence on the straight 

 growth of the stem. 



(c). Freedom from branches. — When the lower branches become 

 sufficiently overshadowed by the development of the crown above, 

 they gradually sicken, and die and fall off before they can attain 

 any size, and leave behind knots or permanent scars in the wood of 

 the trunk at their point of attachment. This process is of course 

 accelerated by the presence of a surrounding leaf-canopy, which 

 should, if the fullest advanatge is to be derived from it, be con- 

 tinued during the entire period of upward growth, i.e., from the 

 thicket stage to the close of the high pole stage. Thenceforward 

 the opening out of the leaf-canopy, unless it is carried to the point 

 of more or less complete isolation, has no harmful effect on the 

 bole. If the trees are isolated, epicorms may of course appear 

 and render knotty the rings of wood formed thereafter. The 

 strehgth and abundance of the epicorms will be in direct propor- 

 tion to the unfavourable nature of the soil and locality for the 

 growth of the species concerned and the unhealthiness or want of 

 vigour of the crown, and in inverse proportion to the age of the 



trees. 



Some species form a more or less long bole even in complete 

 isolation, and are never branched low down even at an early age, 



