THE MICROTOMIST'S VADE-MECUM

which is then thrown into common alcohol, where it remains
for several hours. The gum being now solidified, the prepa-
ration is placed in the well of the microtome and wedged
there by means of small sticks of dry pith well pressed           bi
between the fingers to reduce their volume, and the well is
finally filled with alcohol.                                     thro
Duval considers that this method of imbedding gives far
greater fixity than the usual methods, and notably far greater
than the paraffin process.
Cut with a razor wetted with alcohol. Stain carmine or
carmine and anilin (No. 572), fix the stain with acetic acid,
dehydrate, clear with turpentine, and mount in balsam or but
dammar.
563. Giacomini's Brain-processes (Giacomini's methods )         hd
Although these are in intention macroscopic methods, it          SOIU
appears worth while, both on account of their thorough            1"
success and on account of their suggestiveness, to give an the
account of them here.
The object is to make " dry " preparations of the encephalon;   lo
by which is meant preparations that can be permanently pre-
served in the air. The methods hitherto employed were not
successful because they consisted in making preparations that
were "dry" in the literal sense of the word, that is, deprived   the
of their natural water; and since brain-substance contains       th
88 per cent. of water, such preparations could not of course     sur
be obtained without so great an amount of shrinkage as to
most seriously diminish the scientific value of the result.       eca
The principle of Giacomini's method is on the contrary to         s
retain the natural water of the tissues, or an equivalent for
it, by means of impregnation with a hygroscopic substance,-
glycerin.                                                        few
The process consists of two divisions: 1, hardening; 2,        Tiii
impregnation with glycerin.                                      Sec
1 Communicated to the R. Academy of Medicine of Turin, 7th June,
1878: ' Archivio per le scienze mediche,' iii, No. 2 (1878), p. 11.

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