t attitude the individual hairs slide over one another, and do not
tend to felt or mat; if they did, woe betide the animal. The fact of the
peculiar serrated, scaly structure of hair and wool is easily proved by
working a hair between the fingers. If, for instance, a human hair be
placed between finger and thumb, and gently rubbed by the alternate
motion of finger and thumb together, it will then invariably move in the
direction of the root, quite independently of the will of the person
performing the test. A glance at the form of the typical wool fibres
shown (see Fig. 10), will show the considerable difference between a
wool and a hair fibre. You will observe that the scales of the wool
fibre are rather pointed than rounded at their free edges, and that at
intervals we have a kind of composite and jagged-edged funnels, fitting
into each other, and thus making up the covering of the cylindrical
portion of the fibre. The sharpened, jagged edges enable these scales
more easily to get under the opposing scales, and to penetrate inwards
and downwards according to the pressure exerted. The free edges of the
scales of wool are much longer and deeper than in the case of hair. In
hair the overlapping scales are attached to the under layer up to the
edges of those scales, and at this extremity can only be detached by
the use of certain reagents. But this is not so with wool, for here the
ends of the scales are, for nearly two-thirds of their length, free, and
are, moreover, partially turned outwards. One of the fibres shown in
Fig. 10 is that of the merino sheep, and is one of the most valuable and
beautiful wools grown. There you have the type of a fibre best suited
for textile purposes, and the more closely different hairs approach
this, the more suitable and valuable they become for those purposes, and
_vice versa_. With regard to the curly structure of wool, which
increases the matting tendency, though the true cause of this curl is
not known, there appears to be a close relationship between the tendency
to curl, the fineness of the fibre, and the number of scales per linear
inch upon the surface. With regard to hair and fur, I have already shown
that serrated fibres are not specially peculiar to sheep, but are much
more widely diffused. Most of the higher members of the mammalia family
possess a hairy covering of some sort, and in by far the larger number
is found a tendency to produce an undergrowth of fine woolly fibre,
es