20 BULLETIN 1185, U. S. DEPARTMENT OF AGRICULTURE. 
scars at the nodes long after the cortex is separated from the core 
along the internodes. Figure 18 shows on the left a loose-core test 
made toward the root end of a stem in which retting is incomplete, 
the fibers being gathered in tangled masses at the nodes. On the right 
is another stem removed duri ing y the same stage in retting. In this the 
cortex has been peeled away from the internodes but the fibers cling 
to the leaf scars. 
The efficiency of tests 1 and 2 of the loose-core group is about the 
same, although test 1 may be depended upon to ‘offer resistance to 
separation more nearly up to the end poimt of retting. Test 2 has 
another objection in that the projections of wood at the nodes under 
the leaf scars may catch the fibers and cause them to tangle even after 
retting is completed. 
The tests grouped under the heading “ Leaf-scar tests” are char- 
acterized by a distinct tugging that may be felt at each node as the 
entire cortex is 
ZO peeled away from 
the wooden core. 
The entire cortex 
is used, rather than 
‘a strip, as the entire 
cortex affords addi- 
tional resistance to 
separation, which it 
is necessary to over- 
come in_ splitting 
the cortex on the op- 
posite side of the 
stem from which it 
is pulled. The core 
is held stationary 
and in a horizontal 
| ’ position while the 
cortex 1s pulled ver- 
tically. The great- 
est resistance to sep- 
&) aration was found 
in leaf-scar test 7 
FIG. Step 2 in the loose-core test of retting flax ( fig. 19), in which 
the first Deenk swhere fae cortex has. heen shoved hack, <t6. Cortex i, peeled 
away at right angles 
to the core and toward the panicle end of the stem. Test 8 was almost 
as efficient in this respect as test 7, but had the same objection as the 
second type of loose-core test, since a confused tangling of fibers may 
result while making the test even after retting is completed. Tests 
3, 4, 5, and 6 can. not compare with 7 or 8 in resistance to separation 
of cortex and core, and their relatively low resistance to separation is 
lost some time previous to the completion of retting. Figure 20 
shows the beginning and the end of a leaf-scar test made par rallel to 
the stem. Note how the fibers cling to the leaf scars. 
Of these eight numbered tests, the most efficient members of the 
loose-core and leaf-scar groups remain to be compared. These are 
test 1, in which the loose-core test is made by pulling the wooden 
. 
: 
3 
: 
RB 
