Hello Ross,

As a histologist, I deal with many kinds of tissue fixatives, including
methanol and ethanol, and your observation that methanol is inferior to
ethanol as a tissue fixative is certainly correct.  Unfortunately, the
precise reason for this cannot be adequately explained without getting into
some rather complex organic chemistry, probably not appropriate to this
forum.  In brief though - alcohols are classified as denaturant (or
precipitant, or coagulant) fixatives, which means that the primary molecular
mechanism by which they bring about tissue fixation is denaturation of
proteins.  This means that these compounds can alter the physical structure
or arrangement of protein molecules in ways that render them relatively
insoluble and unreactive, thereby in effect "locking them in place".  A
common example of this is egg albumen (egg white), a liquified protein
which, if dropped into strong alcohol, will turn white and solid, just as it
does during cooking (heat also causes denaturization of proteins).  Anyway,
for reasons I can't address here, methanol is a less effective protein
denaturant than ethanol, which is why it is a poorer tissue fixative.
Methanol is widely used in hematology work, as a blood fixative, where it is
desirable to avoid over-denaturation.

...............................

Philip,

The only way any alcohol (methanol, ethanol, etc.) might "remove" tissue
from inside a shell would be by rapidly dehydrating it, causing it to
physically contract and harden, so that it might subsequently fall out of
the shell as a hardened pellet - if you are lucky.  Perhaps that was Dr.
Clench's meaning.  Or, maybe he just meant that the shriveled up,
contracted, odorless tissue pellet was no longer a problem, even if it
remained inside the shell.  As you observed, there is no reason to expect
that methanol would accomplish this any better than ethanol, propanol, or
other water-miscible alcohols.

Paul M.