ight easily be thrust into the tender parts of the skin, and
there, by reason of their exceeding fineness and driness, not create any
considerable trouble or pain, till by remaining in those places moistned
with the humours of the body, some caustick part sticking on them, or
residing within them might be dissolv'd and mix'd with the ambient juices
of that place, and thereby those _fibres_ and tender parts adjoyning become
affected, and as it were corroded by it; whence, while that action lasts,
the pains created are pretty sharp and pungent, though small, which is the
essential property of an itching one.

That the pain also caused by the stinging of a Flea, a Gnat, a Flie, a
Wasp, and the like, proceeds much from the very same cause, I elsewhere in
their proper places endeavour to manifest. The stinging also of shred
Hors-hair, which in meriment is often strew'd between the sheets of a Bed,
seems to proceed from the same cause.

* * * * *

Observ. XXVII. _Of the _Beard_ of a wilde _Oat_, and the use that may be
made of it for exhibiting always to the Eye the temperature of the Air, as
to driness and moisture._

This Beard of a wild _Oat_, is a body of a very curious structure, though
to the naked Eye it appears very slight, and inconsiderable, it being only
a small black or brown Beard or Bristle, which grows out of the side of the
inner Husk that covers the Grain of a wild _Oat_; the whole length of it,
when put in Water, so that it may extend it self to its full length, is not
above an Inch and a half, and for the most part somewhat shorter, but when
the Grain is ripe, and very dry, which is usualy in the Moneths of _July_,
and _August_, this Beard is bent somewhat below the middle, namely, about
2/5 from the bottom of it, almost to a right Angle, and the under part of
it is wreath'd lik a With; the substance of it is very brittle when dry,
and it will very easily be broken from the husk on which it grows.

If you take one of these Grains, and wet the Beard in Water, you will
presently see the small bended top to turn and move round, as if it were
sensible; and by degrees, if it be continued wet enough, the joint or knee
will streighten it self; and if it be suffer'd to dry again, it will by
degrees move round another way, and at length bend again into its former
posture.

If it be view'd with an ordinary single _Microscope_, it will appear like a
small wreath'd Sprig, with two