REPORTS OF THE SWEDISH INSTITUTE OF EXPERIMENTAL FORESTRY. 
The Form and Form-variations of the Larch. 
By L. MATTSSON. 
(Swedish text, pages 841—922). 
The intention of the present investigation was, to begin with, merely to 
ascertain whether the cubic tables drawn up by Jonson, and applicable to 
Pine and Spruce, could also be used with reasonable accuracy in the valuation 
of Larch-stems. In the course of the work, however, many facts came out 
which were of such importance that they could not possibly be ignored. The 
investigation, therefore, attained a magnitude somewhat disproportionate to the 
importance of the Larch-tree in Swedish forestry. In its present form it is 
chiefly to be looked upon as a preparatory study for future researches into 
the Pine and Spruce based upon the large material of the Swedish Institute of 
Experimental Forestry. 
The material for the investigation and the methods used. 
The material for the investigation is taken from the Institute's great collection 
of sample trees, measured in order to get the volume of the sample plots in 
woods of European and Russian Larch. These trees are measured in sections 
of one metre with the first measurement at o.; m above the stump. More- 
over, the diameter of the stump, and at 1.3; m (breast-high), is measured and 
further the thickness of the bark at the same places on the stems. 
In order to attain the object just mentioned, the following methods were 
used. The stems were divided into form-classes and height-classes, and for 
each of these classes average values were worked out of the diameter-quotients 
at the different heights on the stems above the level of the ground. The 
height-classes were based on the unit-length of one metre with the limits at 
every half metre; that is to say, the height-class 9 m comprises all the trees 
of the height of 38.50—9.49 m. The form-classes were obtained by means of 
the "absolute form-quotient”, that is the diameter at the middle of the stem 
above breast-height divided by the diameter breast-high. This form-quotient, 
which is especially used by JONSON, has the one great advantage over the 
«<spurious form-quotient”, used by SCHIFFEL and others, that it is very nearly 
independent of the height of the stem, which is by no means the case with 
the latter. By using the absolute form-quotient, therefore, it is possible, as 
JONSON (3, 4 and 5) has shown by his investigations, to work out general 
taper-series applicable to all trees of a certain form-quotient. 
In order to obtain such general taper-series, average values, as has already 
been mentioned, were worked out for each form-height group. These values 
were then marked out on cross-ruled paper, and at the curve thus obtained 
the diameter-quotients were read off at every ten percentages of the height of 
stem above breast-height. The taper-series thus obtained can then be used 
in calculating average series for all the height-classes. It is only to be ob 
served that the values from the different height-classes are not of quite the 
same accuracy. Firstly, they are obtained from different numbers of stems, 
