22, BULLETIN 1185, U. S. DEPARTMENT OF AGRICULTURE. 
wooden core, the cortex was only partly retted, and the fibers were 
not sufficiently separated. Hundreds of tests have been made during 
all stages of retting, and without question the resistance to separation 
offered in the leaf-scar test 1s more dependable than the loose-core 
test as an indication that retting 1s not completed. If there is the 
shghtest tendency for the fibers to cling at the nodes the leaf-scar 
test will register a tug at each leaf scar. 
Closely associated with the loss of resistance to separation in the 
leaf-scar test are several changes in the flax stem. Just previous to 
Fic. 18.—Loose-core test in partly retted fiax stems: A, Loose-core test, showing how 
fibers and epidermis slough off and gather in tangled masses (m) that cling to the 
leaf scars (l). B, Stem removed from the retting solution and fibers peeled gently 
away from the wooden core (c). Note how the fibers cling to the leaf scars (l), and 
compare this with Figure 12. 
the positive leaf-scar test a slight swelling at the nodes may be 
observed, and the leaf scars have so nearly disappeared throug 
gradual disintegration that it is difficult to observe more than a tiny 
spot at the center of each leaf scar, a spot that is only slightly darker 
in color than the rest of the stem. If the few stems to be tested are 
