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2             THE MICROTOMIST 1 8 VADE-MECUM
logists of the old school were obliged to do in pre-micro-        vd:
tome times. And the agreement as to this practice is not          jjgit
absent from matters of detail; the great majority of pre- Mge]
parations are made by fixing either with sublimate or a picric    adio of
acid combination, washing-out with alcohol, staining with         tRi
alcoholic borax-carmine, imbedding in chloroform-paraffin,         7a is
cutting with a sliding microtome, and mounting the sections
in series in Canada balsam. By this, which may be called
the general or normal method, the work is blocked-out and           TeO
very often finished; special points being studied, if necessary,   Rt Orr
by special methods, such as examination of the living tissue      treate
elements in sitl, or in "indifferent " media; fixation with      cweril
more precise fixing agents, such as osmic acid or some chromic    oni)
mixture; staining with more precise nuclear stains; dissocia-      theoi
tion by teasing or maceration. Practices antithetical to these    If oro,
principles, such as throwing living tissues into weak glycerine hronic
and leaving them    to die and macerate there, or making           6Te
multiple stains with gaudy but diffusely-staining anilins,         O faort
are not scientific, and are only employed by dilettanti or by a
persons very ignorant of histology. The freezing microtome         rent"
is almost exclusively used by dilettanti and pathologists; I         or
have never seen one employed by a zoologist, nor met with any      combist
account of a zootomical discovery made by means of it. Such
exceptions as might be quoted do not invalidate the position
that the method I have called general or normal really is
such; and as such I now proceed to describe it in sufficient
detail to enable any reader who is unacquainted with it to
study it for himself. The special methods will be found
sufficiently described under their respective headings, so that
it does not appear useful to write a general introduction to
them here.                                                         tal
2. The first thing to be done with any structure is to,
fix its histological elements. Two things are implied by              i
the word "fixing;" first, the rapid killing of the element, so
that it may not have time to change the form    it had during


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