white Paper be placed underneath, may be catched in greater Abundance than can be
imagined without Trial.
PLATE III. FIG. 2.
The Structure and Configuration of several Sorts of Hairs
THE Bristles of an Hog were found of a Substance hard, transparent, and horny,
without the least Appearance of Pores or Holes, as was tried by cutting them
transversely with a sharp Razor, and then examining their cut Ends by a Microscope.
This shewed many wavy Figures thereon, occasioned by the Sawing of the Razor to and
fro, as we may see at the End of the Body A. But notwithstanding Light was cast up-
on them all the various Ways that could be thought on, to make the Pores visible, none
at all could be discovered.
They were neither perfectly round, nor sharp-edged, but prismatical, with divers Sides
and round Angles, Vid. A. Bending them in any Part takes away the Transparency
where the Bending is, makes them look white, and flaws them in that Place.
B represents the Whisker of a Cat cut the cross Way, in the Middle whereof a
large Pith appeared like the Pith of Elder, whose Texture was so compact that no
Pores could be discovered in it ; for tho' in one Position to the Light there seemed an Ap-
pearance of Pores, that Position being alter'd, the Light was manifestly reflected from
them. Which may serve as a Caution never to conclude too rashly on what we view
through Microscopes, or declare our Opinion till we have examined Things in every Light
and Position, and by all the Contrivances in our Power.
C C, and D, are Pieces of the long Hairs of Horses, which appear cylindrical and
somewhat pithy.
E E E represent three Sections of the Hairs of a Man's Head, which were found ge-
nerally almost round, though sometimes a little prismatical. The Part next the Top
was bigger than that nearer the Root. They were throughout transparent, though not
very clear, nor every where of the same Colour, being near the Root like black transpa-
rent Horn, but near the Top-Extremity like Horn that is clear and brown. Their Roots
were pretty smooth, tapering upwards like a small Parsnep, nor could any Filaments, or
other Vessels, like Fibres from the Roots of Plants, be found.
The Top when split, which is common in long Hair, appeared like the End of a Stick
shivered with Beating, with sometimes half a Score Splinters or Divisions.
Our Author says, that as far as he could find, Human Hairs are all solid cylindrical
Bodies, not pervious like a Cane or Bulrush, but without any Pith or Distinction of
Rind ; and imagines those who assert them to be hollow, have not inspected them with
sufficient Care.
Dr. POWER , on the contrary, makes no doubt that every one of our Hairs is hol-
low, which, though our Glasses cannot demonstrate, by reason of their Transparency, is
palpably evinced by that Disease in Poland called the Plica, where Blood drops from the
Ends of the Hairs of the Head, and likewise issues out wherever they are cut ; which,
he thinks, infallibly proves the tubulous Cavity of them. But to this Dr. HOOKE an-
swers, that the Microscope gives no Encouragement to believe our Hairs are hollow ; and
that perhaps the very Essence of the Distemper called the Plica Polonica, may be their
growing hollow, and of an unnatural Constitution.
MALPIGHI afferts the Hairs of Animals to be tubular, that is, composed of a
Number of extremely minute Tubes or Pipes, which he concludes from his Examina-
tion of a Horse's Main and Tail, and the Bristles of a Boar. These Tubes were most
distinguishable near the End of the Hairs where they appeared more open : And he some-
times could reckon above twenty of them. He perceived these Tubes very plainly in
the Hedge-Hog's Prickles, (which are of the Nature of Hairs) together with elegant me-
dullary Valves and Cells.
Mr. LEEUWENHOEK tells us, that an human Hair, cut transversely, shews a Va-
riety of Vessels in regular Figures.
| | Image Size: 240x320 480x640
960x1280 1440x1920 1920x2560
|
