Alexandria daily gazette, commercial & political. [volume] (Alexandria [Va.]) 1808-1812, 1809-09-01
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Son examining the roots OF hairs which nave
been recently plucked opt, | have sometimes IS
seen with the microscope. severai aist'n.'
small 6brss uniting and Joining at the oo.-
.on of the hair. j have no doubt a s g 1ria
go, wore would have been. pereeP''. 49,
had they not been broken on closs
II ness, hires were nearly transparent. In
all microscopical observations on wool and
hair, the greatest attention is requisite, to
prevent any optical illusion from their semi
transpar ncy. The first appearance of a
bright line running up the hair, has induced
many to suppose it was ahollow tube. This
deception arises from the refraction OF the
rays OF light ON the sides of the hair /; So
lid thread of glass will present exactly the
same appearance.
was not aware, when fnst formed
this opinion respecting the structure OF
wool, that it was confirmed by the authority
of that minute and accurate observer of ma.
ture, Lswenhoeck. He says s'each fibre
of hair and woolconsists of long and finer
parts united together by q v;oeoua cement
aud covered with crust or bark" This
is probably nearly the same viscous cement
spread oyer its surface.
The observations of M. Bon, on spiders
and spiders silk, confirm the discoveries OF
Lewenhoeck. The formation Of wool takes
place by slower and more gradual process
under the skin of the animal. Silk acquires
immediate solidity by contact with the air,
owing, as has been be fore stated, to its fila
ments being so extremely minute.
The hbrts of wool and hair being thicker,
require longer time TO become solid BY
desiccation, or by the absorption of oxygen.
That oxygen can be absorbed through the
surface of the skiu, is evident from the we'll
known experiment of placing dark vcnous
blood in closed bladder, and exposing it
to the action of oxygen gas.whcre it acquires
the bright red color of arteIial blood, not
withstanding the interposition OF the blad
der.
= The minute vessels which secrete the
wool or hair forming fluid, unite in the ex-
creting duct near the surface, Of the skin,
where the hair or fibre is formed. This
duct has the appearance of bulb in the roots
of human hair, with an opening nearly SINH
lar in form 10 the mouth OF trumpet, from
whence the hair is protruded. 1t is not i'm.
probable, slhatthe hair may receive by the
lalternatecenstric,'on and expansion of tn.
-osi6ce of shesduct through which it passes
miuute identataons or ridges on its surface,
which occasions the roughnsss we feel when
iti is drawn through the fingers from the
point to the root. To this peculiarly OF
surface, Nj. Monge attributes the telling
quality of wool and hair See DIM. de Chy-
ME. tom. vi. p. 500, Sc.
. The telling of wool or hair, is an effect
resulting. from the external conformation OF
their 6brss, which appear to be formed ei-
Their of small lamina placed over each other,
ina slanting direction from the root towards
the end or point of each fibre, like the
scales of fish lying one over the other in sue
cession from the head to the tail or Of
zones placed one upon another, as In the
horns OF animals from which structure each
fibre, if drawn from its root towards it's
point. viii pass smoothly through the fingers,
but if it be drawn in a contrary direction
from the point towards the root, sensible
resistance and tremulous motion will be felt
by the fingers. This peculiar conformation
disposes the hhres to catch hold of each o.
Their, and as they cannot recede when acted
a.by other bodies, they naturally ad-