14
still used as a working reference manual by
those studying the subject. Miss Lister also
had the distinction of being one of the first
ladies to be elected to the Linnean Society and
also being the only lady president of the Essex
Field Club.
The myxomycetes are commonly known as slime
moulds. The Listers called them mycetozoa
(fungus animals). They occupy an uncomfortable
niche in the order of things, arguments still go
on as to whether they belong in the animal or
plant kingdoms. They have usually been studied
in the past by mycologists because at the fruiting
stage they closely resemble minute fungi and
indeed they usually turn up along with the fungi
amid the decomposition of wood or leaves.
Investigation of the life cycle reveals that the
"animal" goes through flagellate, amoeboid and
plasmodium stages before settling down to produce
sporangia containing spores. As microscopic
organisms in the first two stages they cannot
be seen with the naked eye, but using a microscope
one can observe that if spores are put into water
they release cells which swim away using a
flagellum, a whip like structure on the front
end. They then take an amoeba-like form and
move around on the wet surface of a substrate
feeding on bacteria. The amoebae divide at
frequent intervals and after some days fusion
takes place of thousands of amoebae to form
the plasmodium, which is easily recognised as
the slime one often finds wandering over decaying
wood. The slime is interesting in that it is
not composed of cells, but is a mass of protoplasm
streaming in vein-like structures. Seen under
a low power microscope the protoplasm is seen to
be surging in torrents along the veins first in
one direction and, after coming to a halt, in the