OF THE MINUTE FUNGI OF ESSEX.
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group, and exhibit salient points, which are to be relied upon for
identification.
Examine carefully the dead leaves lying on the ground in moist
situations, when verging upon decay; not those which are exposed
to the full currents of the air but those covered and hidden by other
leaves, so as to remain moist. Holly leaves are generally good hunting.
On these dead leaves the naked eye will detect clusters of little bodies,
growing closely together, but not crowded, with a whitish flattened
globose head, not larger than a good-sized pin, and a thin wiry stem,
not more than a line high. These may belong to the genus
Physarum or Didymium, as the case may be. Perhaps the surface
of the flattened heads will have a mealy appearance, as if dusted with
flour, and this may be distinguished by a pocket lens. When mature
the coating of these heads splits irregularly, and exposes a dark pur-
plish, nearly black powder, the spores, mixed with delicate threads,
and when this is blown away, it is not at all unusual to observe a
blunt prominence standing up in the centre, called the columella. It
looks as though the stem had grown through into the centre of the
little head, or capitulum. Carefully manipulated fine threads will be
seen to radiate from this central columella to the inner wall of the
peridium, or coating of the head. These radiating threads are termed
the capillitium. We need not enter here into all the peculiarities of
these threads, as seen under the microscope, sometimes branching,
and sometimes combined into a network, with the angles thickened,
and enclosing very minute granules of lime. These are all details
to which experience will soon guide you. Here then we have a rigid
stem, supporting a depressed globose head, or capitulum, which con-
sists of a single or double outer membrane, a central projection or
columella (which is sometimes absent), a radiating network of threads
forming the capillitium, and a powdery mass of globose, dark purple
spores, which may be smooth on the surface, but more often spiny.
Upon other dead leaves it may be our good fortune to detect
rather smaller bodies, mostly yellowish in colour, with shorter stems,
but with a head shaped like a wine-glass; the top at first covered by a
little flat disc-shaped white lid, or operculum, then open and exposing
the dark purple contents. These will belong to the genus Craterium,
from the resemblance to a wine-glass. All the essentials are the
same, but the form is different. There is the stem, the head, with
its outer peridium, its central columella, the threads of the capillitium,
and the mass of spores.
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