Growth and Structure of the Wood of Larix. 623 
The tables I-VII show the results of some of these measurements, 
expressed in millimetres. Originally they were carried to two or even 
three places of decimals, like Schwarz’s measurements for Pinus sylvestris} 
It was found, however, that the three parallel measurements of each little 
block varied so much among themselves, owing to the wavy character of 
the annual rings, that figures beyond the first place of decimals were value- 
less, a point which Schwarz seems to have missed through taking only 
a single measurement in each of the four directions of the compass, instead 
of three in each direction, as has been done for the purpose of these tables. 2 
Even in a normally grown tree like the forty-five year old larch of Table I, 
which had never been attacked by the Sawfly, the 6 limit of error ’ was found 
to be so great as to exclude quantities smaller than one-tenth of a millimetre. 
This is shown by Table II, from the same tree, where the numbers are 
expressed as fiftieths of millimetres, reaching consequently to the second 
place of decimals. It has been mentioned that three parallel measurements 
were made in each of the four directions of the compass, making a total of 
twelve for each complete section of the trunk. Series 1 of Table II 
shows the greatest difference of any measurement from the mean of all 
the three taken in that same direction. The mean of these differences for 
the thirteen separate sections of the trunk and averaged over a period of 
six years is 0-15 mm. for the ring-breadth and 0-16 mm. for the autumn wood. 
Perhaps Series 2 of the same table gives a truer idea of the exact degree 
of irregularity of the rings. It shows the greatest difference between any 
one of the twelve measurements and the mean of them all, and the ‘ limit of 
error’ so obtained and averaged, as in Series 1, for the whole tree during 
six years is about half as much as before — 0-09 mm. for the ring-breadth and 
0-08 mm. for the autumn wood. 
TABLE I. SPECIMEN TREE A. 
Height of tree, 68 feet. Sections taken every 5 feet from the base. 
( a ) Ring-breadth in Millimetres. 
1911. 
1910. 
I 9 ° 9 - 
1908. 
I 9 ° 7 - 
1906. 
Average of 
six years. 
Section 
13 
2*0 
2*2 
i-8 
i-8 
1 ’9 
i-i 
i-8 
11 
12 
i *7 
2-2 
2’5 
2-3 
2 ’5 
i- 9 
2-2 
11 
1 1 
i *9 
2-0 
1-9 
2-1 
2*5 
2 • 1 
2*1 
11 
10 
i *5 
2*0 
i-8 
1-9 
2 • 1 
i-8 
i *9 
9 
1*2 
i ‘4 
i-6 
i -7 
i -9 
i*6 
i-6 
11 
8 
0*9 
i-i 
1-2 
i -4 
i-6 
i -5 
i *3 
11 
7 
o-8 
o*8 
1*1 
1*2 
1*2 
I *4 
i*i 
11 
6 
o -7 
o -9 
o *9 
o -9 
1*0 
i*i 
0-9 
11 
5 
o*6 
07 
°7 
o*8 
o -9 
i *3 
o-8 
11 
4 
o*6 
°’5 
o *5 
o*6 
o*8 
1 • 2 
07 
11 
3 
o *5 
o*6 
0*8 
o*6 
o-8 
i-i 
07 
11 
2 
o*6 
o*6 
o-8 
0-4 
0-9 
i-i 
0-7 
11 
1 
o*6 
o-7 
o-8 
1*0 
i*i 
i -4 
o -9 
Average of 
thirteen 
1*0 
1-2 
1 • 2 
i -3 
i ‘5 
i -4 
i '3 
sections. 
2 Schwarz, p. 5. 
1 Schwarz. 
