SUGGESTIONS ON THE MINUTE FUNGI OF ESSEX.
29
At the outset it is advisable to recognize the fact that the fungi
under consideration are developed, externally, from the tissues of
the "host-plant;" and that they are not merely superficial additions
to the plant which supports them, but are like an eruptive disease
breaking through the skin. How the germs got within the plant,
and what circumstances may assist or retard their progress does not
come within the scope of our present inquiry. All we have to do is
to acknowledge them as an internal disease, developed from within
outwards, and exhibiting themselves by eruption of the cuticle. The
appearance that they present, on eruption, is that of a blackish or
brownish or yellowish powder, which powder is the fructification, or
one form of fructification, of the parasite. Examined by the micro-
scope this powder is either unicellular, bicellular, or multicellular,
each form having its own generic name. Unicellular, it may be
Uredo, or Uromyces, &c. ; bicellular, it would be Puccinia; tricellular,
it is called Triphragmium ; and multicellular, either Aregma or Phrag-
midium, both names having been applied to the same thing. In most
instances there is no proper peridium or receptacle, within which the
spores are produced, but in certain cases there is a manifest peri-
dium, and such genera are AEcidium, Peridermium, Raestelia, &c.
Let us assume that we are ready in the early spring to make our
first excursion, and we search diligently amongst the leaves of the
pilewort for the cluster-cups (AEcidium) which are about the
earliest to make their appearance. They are easily seen, both
on the leaves and petioles ; clusters of little cups, with white fringed
margins, and filled with orange-coloured spores. In many species
the cups are clustered together, hence the name of cluster cups, but
in some they are scattered over the leaves. These cups are com-
mon on many herbaceous plants, on several species of Ranunculus,
on violets, on various composite plants, and upon a few shrubs such as
the barberry and buckthorn. In very many instances the one species
is found only on one plant, in some cases on closely allied plants.
When once seen these cluster cups are easily recognised and when
collected may be placed between the leaves of a book, so as to be
kept flat and carried home for examination. The determination of
the species is no difficult matter, so that AEcidium ficariae may be
labelled at once with its name, locality, and date, without even a
microscopical examination. Thus the beginner may soon collect a
series of specimens of different species of AEcidium, by keeping his
eyes open and looking at some books, such as that by Mr. Plow-