Part II. ] 
Caccia : Development of Sal. 
183 
Section 4. — Shape of Stem. 
Laivs which govern the development of the shape of the stem of single trees 
in general : — 
I. — The shape of the stem depends on the total height increment, and on the 
growth of the diameter at all heights, both these factors being to a 
certain extent proportionate to the space allotted to the tree for the 
development of its crown. 
I I. — In a tree which has grown in a crowded wood, the thickest layers of new 
wood are at the top of the trunk, just below the new branches ; and 
these annual layers of wood get thinner towards the foot of the tree, 
until a certain age. 
III. — As the tree ages, the annual rings begin to get broader at the butt, 
producing a swelhng which extends to varying heights, 4 to 12 feet 
from the ground, according to the age of the tree and the growing 
space. 
IV. — The more favourable the locality, the more satisfactory the density of 
the crop, that is, the better the height growth, the greater will be the 
thickness of the annual layers formed near the top of the stem. 
\. — In trees grown in the open the annual layers are either of equal thickness 
throughout the length of the stem, or diminish from top to bottom. 
— Any change of state affecting the conditions under which a tree is grow- 
ing will cause it henceforth to assume the form characteristic of its 
altered environments. Thus, the standards retained after the 
exploitation of the surrounding coppice will soon tend to assume the 
characteristic conical shape of isolated trees. 
Ml. —It follows that whenever it may be required to compare the cubic con- 
tents of a tree before and after its isolation, it will be necessary not 
only to take account of the increase in girth at breast-height ; but also 
of the change w'hich may have occurred in the shape of the stem 
throughout its length. 
The outlines of typical Sal steins, at various periods of their develop- 
ment, and for trees grown under definite conditions are best indicated 
by a graphic representation of a cross section of the stem (Figure 2) : 
but suflacient data are not at | resent available to lead to any definite 
conclusions. 
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