■ mil inn mil mil mil iiiii mi mi 
PEDIGREED FIBER FLAX. 7 
was stronger and less likely to vary than either the basal portion 
or the top ; so this portion was always used in making the strength 
tests. The stem diameter was measured at a point in the middle of 
the portion chosen for the test, and if several stems were of equal 
breaking strength the one with the smallest stem diameter was con- 
sidered the strongest. In order automatically to determine the 
stems with the greatest strength per stem diameter, the prac- 
tice of dividing the breaking strain by the diameter was adopted 
in 1919. This gives the strength per millimeter of diameter. The 
manner of making the strength tests is as follows: The stems are 
water retted at a uniform temperature so as to loosen from the 
wood of the stem the cortex in which the fibers are located. A 
piece 15 centimeters long is cut from the center of the stem chosen 
for the test. The wood is broken along the middle 2 to 3 centi- 
Fig. 4. — Completion of a strength test. Good fiber is indicated by breaking at several 
points and snapping away from the stem. 
meters of this piece by rolling a glass tube over the stem without 
breaking the fibers. The pieces of wood are removed by working 
the stem with the fingers, and nothing is left but the fibers and 
those portions of the cortex which remain clinging to them. The 
strength tester (Fig. 4) is a horizontal machine with two pairs of 
jaws, between which the ends of the individual piece of stem are 
fastened. One jaw is rigid and the other, which is movable, exerts 
a pull on the fibers which is registered in kilos to the tenth place. 
This figure is known as the breaking strain. 
Eecords for 1917 and 1918 show that the extent of basal branching 
is an inherited character, and it has therefore served as an eliminator. 
Seed-flax varieties have as a rule four or more basal branches, and the 
unselected fiber flaxes have two to four. The quality of fiber is poor- 
est in the White-Blossom Dutch variety, the fiber flax with the largest 
