24 BULLETIN 1185, U. S. DEPARTMENT OF AGRICULTURE. 
through water in order to reach a decision. Figure 23 shows an 
epidermis test after the fibers have been swished through water. 
The fibers here are well separated, and the pieces of cuticle have 
separated from the fibers at all points except at the leaf scars where 
the waterproof unions formed by the suberin between the fibers and 
the epidermis are not entirely 
disintegrated. Retting is al- 
most complete when this stage 
is reached, and the process 
should be watched closely. It 
is possible that these remnants 
of the epidermis could be re- 
moved by breaking and scutch- 
ing. 
Sellergren states that traces 
of pectin and parenchyma cells 
are not entirely removed dur- 
ing the process of retting and 
that the removal of these im- 
purities during the processes 
of breaking, scutching, and 
combing gives the fiber in- 
creased luster.1t Retting should 
be carried on, however, up to 
the very last stage and until 
serious weakening of the fiber 
would result if continued. The 
cleaner the retting process 
leaves the fiber the less will be 
the necessity of scutching to 
remove the nonfibrous portions 
and consequently the less will 
be the wastage of fiber result- 
ing from the impacts of the 
; ; scutching blades. 
Good samples of fiber have 
&) been obtained through the use 
of the leaf-scar test. In some 
of these samples the fiber was 
Fic. 20.—Leaf-sear test in partly retted so well separated from the 
flax, made toward the root end of the wooden core that no scutching 
Tee aaa Paet ot the ee; was necessary, and it could be 
and oie et ane onde ihe. et. hand | hackled «directly atu 
fibers cling to the leaf scars where the running 1t through the brake. 
core in: ther letLhend ewe an ad he, Use; of. the, loese-cone aaa 
in our experimental work, has 
been discontinued, being replaced by the leaf-scar and epidermis tests 
combined. The retting process has been carried on as far asa positive 
epidermis test without any apparent loss in fiber strength. It is be- 
11 Sellergren, Gustay. Inhemska fibervixter. Jn K. Landtbr. Akad. Ilandl. och Tidskr., 
arg. 60, p. 388-424, 13 fig. 1921. (Manuscript translation by Ebba Oleson Campbell, p. 
10. On file in the Office of Fiber Investigations, Bureau of Plant Industry.) 
