Introduction to Fungi, Third Edition

52 PROTOZOA: MYXOMYCOTA (SLIME MOULDS)
Fig 2.11 Trichia floriforme. (a) Undehisced
sporangia. Note that the sporangial stalks are
continuous with the hypothallus. (b) Dehisced
sporangia releasing spores by twisting of
elaters. (c) Elaters and spores.
A further interesting feature of P. polycephalum
is the behaviour of the plasmodium
and the manner in which its actions are coordinated.
Little work has been carried out
beyond descriptions of striking phenomena.
One is the ability of P. polycephalum plasmodia
to find the shortest way to a food source through
an artificially constructed maze (Nakagaki, 2001).
Another is the pattern of veins which is established
when different regions of a plasmodium
are presented with food sources; the configuration
of the plasmodium has been called a ‘smart
network’ because it presents the shortest
possible total length of veins to provide good
interconnections while making allowances for
blockage of individual veins (Nakagaki et al.,
2004).
When separate plasmodia of P. polycephalum
or other species meet, two reactions are possible,
i.e. a compatible reaction in which the plasmodia
fuse and their veins coalesce (Fig. 2.8b) or an
incompatible reaction in which the plasmodia
fail to fuse and move away from each other, or
fusion is attempted but stalls and is followed by
death of the fusion regions of both plasmodia
(Fig. 2.8c). This is called the lethal reaction.