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Hooke, Robert, 1635-1703 / Micrographia: or some physiological descriptions of minute bodies made by magnifying glasses : with observations and inquiries thereupon
(MDCLXVII [1667])

Observ. XXIV. Of the surfaces of rosemary, and other leaves,   pp. 141-142

Observ. XXV. Of the stinging points and juice of nettles, and some other venomous plants,   pp. 142-147

Page 142

142                  MICROGK A HP IA.
     before in the i 9. Obfervation noted on Rofe-leaves, is of a quite differ-
     ing kind, and 1eems indeed a real Vegetable, diflinft from the leaf
        Thirdly, among thefe fmall buffies are observable an infinite company
     of fmall round Balls, exadly Globular, and very much resembling Pearls,
     namely, C C C C, of thefe there may be multitudes obferv'd in Sage,
     and feveral other Plants, which I fuppofe was the reaf6n why Athanafl"
     Kircher fuppofed them to be all cover'd with Spiders Eggs, or young
     Spiders, which indeed is nothing elfe but fome kind of gummous exfu-
     dationwhich is always much of the fame bignefs. At firft fight of thefe,J
     confefs, I imagin'd that they might have been fome kind of matricer
     nourifhing receptacles for fome fmall Infed, juft as I have found Oak-
     apples, and multitudes of fuch other large excrefcencies on the leaves
     and other parts of Trees and Ihrubs to be for Flyes, and divers other
     feds, but observing them to be there all the year, and fcarce at all
     change their magnitude, that conjcdure feem'd not fo probable. But
     what ever be the ule of it, it affords a very pleafant object through
     Microfcope, and may, perhaps, upon further examination, prove very
     Obferv. XXV. Of the flinging points and juice of Nettles, and
         fome other venomous Plants.
       A Nettle is a Plant fo well known to every one,as to what the appear-
       A5 ance ofit is to the naked eye,that it needs no defcription;and
       are very few that have not felt as well as feen it; and therefore
it will be
       no news to tell that a gentle and flight touch of the kin by a Nettle,does
       oftentimes not onely create very fenfible and acute pain, much like
       of a burn or fcaldbut often alfo very angry and hard fwellings and
       mations of the parts, fuch as will prefently rife, and continue fwoln
       vers hours. Thefe observations, I fay, are common enough; but how
       pain is fo fuddenly created, and by what means continued, augmented
       for a time, and afterwards diminifh'd, and at length quite exftinguifih'd,
       has not, that I know, been explain'd by any.
       And here we muft have recourfe to our Microfcope, and that will, if
       almoft any part of the Plant be looked on, fbew us the whole furface
       it very thick fet with turn-Pikes, or fharp Needles, of the fhape
       represented in the x 5. scheme and firit Figure by A B, which are
       alfo to the naked eye; each of which coniIifs of two parts very diftind
       for fhapeand differing alfo in quality from one another. For the part
       is fhaped very much like a round EBodkinfrom B tapering till it end
in a
       very fharp point; it is of a fubftance very hard and ti ff; exceedingly
       tranfparent and cleer, and, as I by many trials certainly found, is
       from top to bottom.
       This I found by this Experiment, I had a very convenient Micro-

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