In short, upon the nature and arrangement and conformation of the scales
on the hair-shafts, especially as regards those free upper edges,
depends the distinction of the value of many classes of wool and fur.
These scales vary both as to nature and arrangement in the case of the
hairs of different animals, so that by the aid of the microscope we have
often a means of determining from what kind of animal the hair has been
derived. It is on the nature of this outside scaly covering of the
shaft, and in the manner of attachment of these scaly plates, that the
true distinction between wool and hair rests. The principal epidermal
characteristic of a true wool is the capacity of its fibres to felt or
mat together. This arises from the greater looseness of the scaly
covering of the hair, so that when opposing hairs come into contact, the
scales interlock (see Fig. 9), and thus the fibres are held together.
Just as with hair, the scales of which have their free edges pointing
upwards away from the root, and towards the extremity of the hair, so
with wool.
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