INTRODUCTORY                         5
it  continued (at the melting point of the pure paraffin) until
6    the whole of the chloroform      has been driven off, which
may be conveniently tested by the smell.       The object is
then imbedded in a convenient position, and sections are
e    cut (see IMBEDDING METHODS). The sections, cut dry, are
mounted in series on a slide by the method of Frenzel, or by
that of Schillibaum, or by that of Mayer (see SERIAL SECTION
METHODS).     The paraffin is now removed and the sections
are stained, generally with borax-carmine, which two opera-
tions are performed as follows: A series of glass tubes large
enough to hold a slide is filled with the following reagents,
and arranged in the following order: Turpentine (or naphtha);
absolute alcohol; 90 per cent. alcohol; 70 per cent. alcohol;
&    alcoholic borax-carmine; 70 per cent. alcohol acidulated with
HC1; 90 per cent. alcohol; absolute alcohol. The slide,
ri  having been warmed to the melting point of the paraffin, is
to   plunged into the turpentine, which removes the paraffin;
then passed through the tubes with the successive alcohols
O    into the stain, from which it is brought into the successive
Ing  alcohols of the ascending series, which wash out the stain
i    and dehydrate the sections. Nothing more now remains to
t00  be done but to treat the sections with a drop of benzol or
gh  turpentine, and to add Canada balsam and a covering glass.
iid  The plan of staining sections on the slide is of very recent
ds   introduction; before it had been worked out the practice was
o    to stain structures in toto, before cutting sections. And in
4 cases in which structures are sufficiently small and permeable
the  to allow of satisfactory staining in this way, and if it be not
me   essential to save time, this plan is quite as good as the one
are  described. In this case the object after having been fixed and
E2   washed out is taken while still on its way through the lower
W    alcohols (it should not be allowed to proceed to the higher
Eis   grades of alcohol before staining) and passed through a bath of
of   alcoholic borax-carmine (or other alcoholic stain) of sufficient
te   duration, then dehydrated with successive alcohols, passed