The X-Ray Interpretation of the Structure and Elastic Properties of Hair Keratin

Abstract

RECENT experiments,¹ carried out for the most part on human hair and various types of sheep's wool, have shown that animal hairs can give rise to two X-ray ‘fibre photographs’ according as the hairs are unstretched or stretched, and that the change from one photograph to the other corresponds to a reversible transformation between two forms of the keratin complex. Hair rapidly recovers its original length on wetting after removal of the stretching force, and either of the two possible photographs may be produced at will an indefinite number of times. Both are typical ‘fibre photographs’ in the sense that they arise from crystallites or pseudo-crystallites of which the average length along the fibre axis is much larger than the average thickness, and which are almost certainly built up in a rather imperfect manner of molecular chains—what Meyer and Mark² have called Hauptvalenzketten—running roughly parallel to the fibre axis.