STUDIES in these laboratories have suggested that the arrangement ofscales in the cuticles ofmammalian hairs can be more accurately revealed by the exam_ination of fibre sections, using ultra-violet light, than by the use of the electron microscope
Thin transverse and longitudinal sections of human hair, hog bristle, alpaca and wool have been prepared at thicknesses varying from one to five microns
In human hair these scales are approximately 0·33 micron thick and approximately 30 microns in length ; the latter measurement being taken from a point on the lower margin of the scale, which abuts on to the cortex, to a point on the upper margin of the scale which is on the surface of the fibre. Of this length, only about one-sixth forms the outer surface of the fibre, the remaining five-sixths being covered by the adjacent overlapping scale
Longitudinal sections of Lincoln and Leicester wool fibres show that individual scales are approximately the same length as the scales in human hair but in some cases thicker, up to 0·66 micron
The proportion of longitudinal overlap is the reverse of human hair, namely, only approximately one-sixth of the total length is covered by another scale, and fivesixths of the length forms the outer surface of the fibre
Transverse section of Leicester wool fibre. Both transverse and longitudinal sections of wool fibres show that the cuticle is much thinner than the cuticle of human hair, hog bristle or alpaca, due to a different arrangement of scales
If the dialysed aqueous solution of the fibroin is dried slowly, films are obtained with the diagram of 'Silk I'