Estimation of Cortical Components in Various Wools

Wools varying widely in diameter and crimp. from sheep of several breeds and ages. were stained with various reagents chosen to give high contrast between ortho- and paracortical segments. The brown to black sulfide stain produced in wools by sodium plumbite, selective for the paracortex, was measured quantitatively and observed to in crease with diameter. The greatest rate of change occurs in the fine diameter region. Wools shorn from sheep at different ages show lead sulfide staining increasing with age at shearing. Wool fibers which have been elongated or supercontracted show increased staining, which reflects the mechanical damage. The same wools were stained with acid nickelous nitrite, preferentially staining the ortho segment. It was verified that in this case the order of staining of the various wools is the reverse of that with plumbite. Solubility in an aqueous solution of urea and monothioglycol is shown to increase regularly with the degree of staining in the nickel solution. Bromine water also preferentially stains the orthocortex. Finally, paralleling the staining behavior, the stress in wool at 30% extension (wet) increases generally with diameter as well as with increasing maturity of the sheep.