SERIAL SECTION MOUNTING

strong solution of shellac in anhydrous kreasote." (Warm
the kreasote to make the solution.) " Care must be taken to
have as little as possible on the slide."
Bourne notes that the slides should be heated for at least
half an hour at a temperature two or three degrees above the
melting-point of the paraffin; and that the turpentine should
be flooded on to the sections from a small pipette while the
parafIn is still molten. This dissolves melted paraffin instan-
taneously, and precipitates the shellac fastening the sections
to the slide. The turpentine is allowed to flow off and is
replaced by new, until all the paraffin is removed. The slide
is then drained, wiped, and the cover put on. Some very fluid
balsam  is previously put on the cover-glass, which is turned
over and quickly lowered. The balsam dissolves the shellac, so
that if the cover be not quickly lowered the sections may
shift or delicate sections come to pieces and float over the
slide.
268. Paraffin and Xylol Section-fixing Methods (Gaule's
section methods 1).-Sections are cut from a paraffin-iibedded
object in the usual manner. The point now is, to dissolve
i away the paraffin from the sections without floating away any
part of the structures from its natural position.
A slide is moistened with alcohol, the sections are arranged
in it by means of a camel-bair brush, also moistened with
alcohol; the slide is slightly warmed so as to cause the section
to stick to the slide; a cover is put on, and a solution of
Canada balsam in xylol (equal parts of each) run underneath
it. If the sections are not thicker than _,,th mm., they will
be cleared at once, and nothing remains but to refill the cell
day by day as the xylol evaporates, in order to have a perfect
mount. If, however, the sections are thicker than 71th mm.,
they will contain more paraffin than the xylol balsam can
dissolve. In that case, the excess of paraffin must be removed
by means of a drop of pure xylol (the sections being first
I ' Arch. Anat. u. Phys.' (Phys. Abth.), 1881, p. 156.

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