THE FORM AND FORM-VARIATIONS OF THE LARCH. LXKXXIX 
The density during the time of growth just mentioned is settled by com- 
paring the mean diameter of the wood obtained by measurement and the 
one mean diameter which by empirical knowledge was to be expected. 
The results obtained will certainly prove to be of general validity. In 
order to settle this fact, however, very close investigations are needed, especially 
concerning the form-variations within the woods. 
Such investigations concerning the Fir have already been planned by the 
State Institute of Experimental Forestry. 
Application of the results obtained. 
The results just stated are of a more general significance. With the aid of 
these it is then possible to arrive at the more particular objects of this re- 
port, that is, form-factors and bark-percentages for larch-stems of different 
shape. 
In making out the form-factors the following line of thought is followed. 
As the investigation has shown, the wood-stem and the bark vary quite in- 
dependently of each other. The form of the wood-stem can be obtained 
with relatively great accuracy from the height of the stand and the density 
of the same during the time of growth. In order to get a full idea of the 
form of the wood-stem, therefore, it is not necessary to make special measure- 
ments in the stand. 
The case is somewhat different in dealing with the bark. The volume of 
the bark varies with the bark breast-high, the taper. of the bark, and the form 
of the wood-stem. Of these three facts, the two concerning the bark vary 
within very wide limits without any correlation with certain characters of the 
stand. '”The volume of the bark, therefore, cannot be determined without 
special measurements, which, to some extent at least, cannot in practice be 
performed on growing stems. 
As a summary of the facts just mentioned we can say this: the mean 
wood-stem of a growing stand can be made out with relatively great accuracy; 
the bark-volume can only be approximately determined; and, therefore, the 
sum of both at least with less accuracy than the wood-stem alone. It looks, 
therefore, as if the most practical way of measuring a stand should be to 
determine the volume of the stand without bark and to the value thus ob- 
tained add the less accurate bark-volume. In accordance with these argu- 
ments different form-factors are made out for the wood-stem and for the bark. 
As soon as the taper series are obtained, there is no difficulty in getting 
the volume of a stem above the diameter breast-high. This volume divided 
by the cylinder of the same height gives the absolute form-factor of the stem. 
If the distension by the root at the diameter breast-high reaches an amount 
of p per cent, this fact will enlarge the cylinder by 2 4 per cent, whereas the 
volume of the stem is nearly unchanged. The absolute form-factor just 
obtained, therefore, if the distension by the root is taken into consideration, 
is to be divided by the figure (1+ 247). If the value thus made out is multi- 
3 IT— 5 : : 
plied by the factor TS where 89 is the total height of the stem, 2 the 
height of measurement, thatis 1.3; mtr, and s the height of the stump, we 
have obtained a factor which indicates the relation between the stem above 
