In weakness and disease the number of scales in
a given hair-shaft diminishes, and these become finer and less
pronounced. The fibres themselves also become attenuated. Hence when
disease becomes death, we have considerably degraded fibres. This is
seen clearly in the subjoined figures (see Fig. 13), which are of wool
fibres from animals that have died of disease. The fibres are attenuated
and irregular, the scale markings and edges have almost disappeared in
some places, and are generally scanty and meagre in development. It is
no wonder that such "dead wool" will be badly adapted for felting. "Dead
wool" is nearly as bad as "kempy" wool, in which malformation of fibre
has occurred. In such "kemps," as Dr. Bowman has shown, scales have
disappeared, and the fibre has become, in part or whole, a dense,
non-cellular structure, resisting dye-penetration and felting (see Fig.
14).
[Illustration: FIG. 13.]
[Illustration: FIG. 14.]
One of the physical properties of wool is its hygroscopicity or power of
absorbing moisture.
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