THE FORM AND FORM-VARIATIONS OF THE LARCH. LXXXVII 
can be worked out. The relative series obtained is graphically illustrated in 
fig. 4, page 878. By means of this series the bark-percentage for all the 
diameter-classes in a stand can be found as soon as the value for one class 
is known. | 
To be able to ascertain whether the thickness of the bark is possibly in- 
fluenced by the density or any other character of the stand, it is desirable 
to obtain one figure indicating this quality. Such a figure, of course, can 
be made out in many different manners. In this investigation the following 
method was used. The difference between the value for one diameter-class, 
as settled from the average series and from the direct measurements, was 
ascertained. The value thus obtained was divided by the value indicating 
the variation (standard deviation) of bark-percentage breast-high observed in 
all the stems of the material belonging to the diameter-class in question. An 
average of those values was then made out. The value thus obtained is the 
figure desired. In table 14, page 881, some stands are arranged according 
to the thickness of bark worked out in the manner just described. In the 
same table the ages, degrees of density and some other characters of the 
stands also are brought in. 
In dealing with the taper of the bark, it very soon became plain that it 
was a quality quite independent of the taper of the stem. The absolute 
form-quotient, therefore, could be quite put aside. As a measure of the taper 
of the bark the bark-quotient at the middle of the stem was used. This 
factor varied extraordinarily (table 18, page 887). At the same time, how- 
ever, the connection between the bark-quotients at the middle of the stem 
and at some other place on the stem, for example at 25 percentages of the 
height of stem above breast-height, was very close. Therefore it appeared 
suitable to make out some taper-series in quite the same manner as was be- 
fore used in dealing with the taper of the wood stem. Such taper-series for the 
European as well as the Russian larch are to be found in a graphical form in 
fig. 8, page 909. 
General results. 
The results of the investigations are of two kinds. Firstly, a comparison 
is established between the European and the Russian larch; secondly certain 
facts are obtained which may possibly be of some importance in practical 
tree-measurement, not only concerning the larch but possibly also concerning 
other species of trees. 
The results first mentioned may be summarized as follows. 
The general construction of the stem of the two larch-species appears to 
be quite the same. Scarcely any difference is to be observed between the 
taper-series now obtained and such as were earlier worked out by JoNSON for 
the Pine. 
Variations according to form for trees of the same form-quotient appear. 
These variations are so great, that, as investigations of the European larch 
show, the form-quotient can be made out from graphically levelled measure- 
ments at 25 percentages of the height of stem with a standard error of the 
amount of + 2.1 form-class-units (percentages of the diameter breast-high). 
It looks as though the upper parts of the higher stems were not quite as 
full-bodied as the same parts of the lower stems; but the difference is a very 
small one. In a higher degree, however, the stems of the greatest and smallest 
