inside the follicle by the exuding therefrom of a plastic liquid or
lymph; this latter gradually becomes granular, and is then formed into
cells, which, as the growth proceeds, are elongated into fibres, which
form the central portion of the hair. Just as with the trunk of a tree,
we have an outer dense portion, the bark, an inner less dense and more
cellular layer, and an inmost portion which is most cellular and
porous; so with a hair, the central portion is loose and porous, the
outer more and more dense. On glancing at the figure (Fig. 6) of the
longitudinal section of a human hair, we see first the outer portion,
like the bark of a tree, consisting of a dense sheath of flattened
scales, then comes an inner lining of closely-packed fibrous cells, and
frequently an inner well-marked central bundle of larger and rounder
cells, forming a medullary axis. The transverse section (Fig. 7) shows
this exceedingly well. The end of a hair is generally pointed, sometimes
filamentous. The lower extremity is larger than the shaft, and
terminates in a conical bulb, or mass of cells, which forms the root of
the hair. In the next figure (Fig. 8) we are supposed to have separated
these cells, and above, (a), we see some of the cells from the central
pith or medulla, and fat globules; between, (b), some of the
intermediate elongated or angular cells; and below, (c), two flattened,
compressed, structureless, and horny scales from the outer portion of
the hair. Now these latter flattened scales are of great importance.
Their character and mode of connection with the stratum, or cortical
substance, below, not only make all the difference between wool and
hair, but also determine the extent and degree of that peculiar property
of interlocking of the hairs known as felting. Let us now again look at
a human hair. The light was reflected from this hair as it lay under the
microscope, and now we see the reason of the saw-like edge in the
longitudinal section, for just as the tiles lie on the roof of a house,
or the scales on the back of a fish, so the whole surface of the hair