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other direction. By timing the movements one
can judge the direction in which the plasmodium
is moving. How the plasmodium moves is a little
understood process, but it has been shown to
contain two substances which react in a similar
way to those found in contractile muscle. The
purpose of movement is to feed on bacteria, fungi
and many other things lying nearby. It is well
known that they feed well on rolled oats and
it is on this medium that they are cultured in
laboratories. The conditions which trigger the
final phase are obscure, but it is generally
thought that the advent of dryer conditions or
lack of food cause the slime to contract into
blobs which develop into the sporangia. It
also appears that in the case of yellow coloured
plasmodia, alternate exposure to darkness and
light also contributes to the process.
It is at the sporangial stage that myxomycetes
are identified. At first glance they look like
minute fungi; many species being around 1 mm
in height, although there are a few which grow
to a centimetre or more. Examination of a number
of species reveals a variety of shapes, sizes and
colours. Some have stalks, others are sessile
and some have lime deposits on the surface
of the sporangium. It is interesting to find
a great variety of form within a specie. For
example, some specimens have stalks and others
are sessile. This has led to widespread
difficulties in the past, with "new" species
being described when in fact the specimen was
merely an ill-formed or variation of an already
named specie. Fluctuations in temperature and
humidity are sometimes responsible for these
variations, although it is not uncommon to find
differing forms even within a single fruiting.