When
left
overnight
the
spores
germinate
into
vegetative
cells.
These
are
killed
during
the
second
days
exposure
to
steam
for
30
min.
Again,
the
material
is
cooled,
and
the
few
remaining
spores
germinate,
which
are
killed
on
the
third
day
exposure.
This
method
is
particularly
important
in
modern
microbiology,
for
sterilising
those
objects
which
could
not
be
sterilised
by
autoclave.
The
instrument
used
is
Arnold
steriliser.
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