ì î:
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E X P L A I N E D BY THE MICROSCOPE. ij
The very courfe andprogrefs of the fluid may be ibewn in this part, even by an eafier PLATE
preparation ; only that difièrent Rinds muft be fought for this purpofe ? the velTels in
forae being larger than in others. Repeated trials have fhewn rtie, that the whole progrefs
may be eafily marked, in the three following kinds, with only a tinflure of cochineal.
Put half an ounce of cochineal in powder into half a pint of fpirit of wine j fet it
in a warm place, and fliake it often, for foiir days j then filter off the clear t inture ;
put an inch depth of this into a cup, and fet upright in it pieces of the Rind of Aih,
White Willow, and Ozier ; prepared, as has been direiled, by maceration in water ;
for in that way one trouble does for a hundred kinds. Let an inch of the Rinds alfo
ftand up out of the tindure. After twenty-four hours take them out, clip off the
part which was immerfed in the fluid, and fave the reft for obfervation.
Here is a farther inftance of the divifibility of matter. Tho' colour difappears in a Fig. 4.
great meafure under the Microfcope, the more as the power of magnifying increafesj yet
in the flrft of thefe Rinds, that of the common Aih, the courfe of the veffels is very
diftinftly and beautifully feen ; for they and they only are crimfon. In this fpecies
the colouring liquor enters only by the open ends of the veflels -, for the mouths at their
fides feem too much contrafted in the drying to receive it : it afcends their whole length,
and fliews itfelf at the exterior apertures or mouths, but penetrates no farther. Fig. 4.
In the Willow Rind, Ihewn at Fig. 5. the interilitial fpaces, as well as the veffels, are Fig. 5.
crimfon : therefore, among the vaft variety of conftruftion between the Rinds of feveral
trees, the mouths of the fécond feries are in this larger than in the Aih. Jt muft
be fo ; becaufe the colouring liquor was the fame to both, and only the conflrruflion
of the body itfelf could in one inftance have admitted it through paffages which were
clofed to it in the other.
In the Willow, the apertures of the third order iìiìl refufing paffage to the coloured Fig. 6.
fluid, the Blebs retained their natural Olive complexion ; but 'tis not fo in the Rind of
Ozier, there every feries of mouths are open enough to let out the crimfon liquor, and
the whole fubftance of the Rind is ftained with it. Fig. 6.
From hence Philofophy will judge (and it wiU judge with fafety) why the Leaves of
the Aih appear later than thofe of the White Willow, and why the Open Ozier precedes
even thefe. Elder and Goofeberry Rinds admit this univerfal tinge more readUy
than Ozier j but they are not fo eafily feparated and prepared. The fame philofophic
truth arifes alfo here : their texture is the openèit of that in any Rinds ; and 'tis there-,
fore they appear the heralds of the Spring, and harbingers of eve^ other verdure.
C H A P .