12 BULLETIN 1185, U. S. DEPARUMENT OF AGRICULTURE. 
the stem is the last to be retted. Very close to the time when retting 
is complete the fiber bundles separate into several smaller units, and 
the cuticle is detached from the outside of the stem. This study 
also points out that retting proceeds from the cambium layer toward 
the outside of the stem and that the waterproof union of the fiber 
bundles and wood branches formed by the leaf scars at the nodes, 
make retting at the nodes more difficult than in the internodes. These 
conclusions indicated that the search for a completion-of-retting test 
should be focused on the outside surface of the stem rather than on 
the area between the wooden core and the cortex occupied by the 
green inner bark or cam- 
bium layer. 
SOME MACROSCOPIC 
AND EXTERNAL 
CHANGES IN THE 
FLAX STEM DURING 
RETTING. 
Some retters claim 
that sliminess of the 
stem 1s closely associated 
with the end point of 
retting, and others claim 
that stem brittleness is 
thus associated? In 
order to eliminate any 
chance of missing a 
change that is at all as- 
sociated with the end 
point of retting, a list 
ve . . . Oo 
lic. 7.—Changes in the appearance of the cortex of Nias made of the changes 
flax during ‘the last stages of retting. The fiber mentioned in the litera- 
bundles here shown are entirely free from impurities SAR a: , pace 
and are split lengthwise into fibers of suitable width, ture and those that have 
indicating the completion of the retting process. heen noted in this studv. 
x 10. : 
The approximate — se- 
quence of these changes was determined by studying the retting proc- 
ess repeatedly. Observations were made every six hours and records 
were taken of the time when each change was first noted. Such changes 
as sinking of the straw, brittleness of stem, and maximum sliminess of 
stem are of little value, as they take place too far in advance of the 
completion of retting. Brittleness of the stem merely indicates that 
retting is proceeding satisfactorily and that stagnation has not oc- 
curred. 
The loosening of the cortex from the wooden core, as determined by 
the Belgian or loose-core test, also occurs at times several days before 
the completion of retting ina 14-day retting period. Toward the end 
of retting the stems became gradually lighter in color (fig. 9), 
changing from a yellow-brown to a very hght yellow or almost 
10 Huntley, F. A. Fiber flax investigations. Wash. Agr. Exp. Sta. Bul. 33, p. 18. 
898. 
