HARDENING AGENTS

CHAPTER XVIII.
HARDENING AGENTS.
200. If this chapter had been written ten years ago, it
would have had a far greater importance than can now be
claimed for it, and I should have considered it necessary to
treat it with far greater detail than now seems desirable.
The reason of this is that methods of imbedding have now
been brought to such a degree of perfection that the thorough
hardening of soft tissues that was formerly necessary in order
to cut thin sections from them is now, in the majority of cases,
no longer necessary; by careful infiltration with paraffin or
some other good infiltration mass, most soft objects can be
satisfactorily cut with no greater an amount of previous
hardening than is furnished by the usual passing of the
tissues after fixing through successive alcohols in order to
prepare them for the paraffin-bath. Almost the only excep-
tions to this statement are, I believe, to be found in the cases
in which it is desired to cut very large sections, such as sec-
tions of the entire human brain. Such an organ as this cannot
be duly infiltrated with alcohol in a few hours, and it is
doubtful whether it can be duly infiltrated with paraffin or any
other imbedding mass in any reasonable time. The processes
employed for hardening such specimens as these will be
described when treating of the organs in question; in this
chapter I confine myself to such general statements concern-
ing the employment of the usual hardening agents as appear
likely to be generally useful.

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