100
EPPING FOREST
can be distinguished by the naked eye, but the beauty of
most of them can be discerned by the use of low powers.
The most satisfactory places to search are swampy
ground, amongst bog moss, such as some localities
about High Beach, the slopes in front of the King's
Oak, and numerous other places in the Forest. Most
of the species of Closterium are large, and can be seen
in the collecting-bottle held up to the light. Closterium
lunula at High Beach; Closterium Ehrenbergii near
Chingford; Closterium striolatum on the Loughton
side ; and other species at High Beach, Snaresbrook,
and Walthamstow. The large rounded fronds of
Micrasterias rotata and Micrasterias denticulata occur
in boggy pools about High Beach, Wood Street, and
elsewhere. Euastrum oblongum and Euastrum crassum
are about the finest of the genus, and these have been
obtained at High Beach. Of the species of Cosmarium,
such as Cosmarium margaritiferum, Cosmarium botrytis,
are the most conspicuous, and these have been obtained
at High Beach and Wood Street. One or two species
of Xanthidium have been collected at High Beach.
Smaller species, such as those of Staurastrum, Arthro-
desmus, and the more minute species of Cosmarium, are
by no means uncommon. These will sometimes be
found in conjugation. More than fifty different species
may be relied upon, large and small, in the Forest
district.
Filamentous Algae. It is not uncommon to call all the
forms of filamentous Algae by the general name of
confervae but this is an error which should be avoided.
Most of the Algae which have a threadlike form consist
of a great number of cells joined end to end, and are at
first attached to some fixed object, from which they are at
length severed, and float freely in the water. They are
of many kinds, and some of them of great interest,
especially when they exhibit their fructification. Fore-
most in interest are the species of Spirogyra, in which the
green endochrome is arranged in each cell, in the form of
one or more spiral bands. A dozen or more species
may be met with in the pools and clear ponds scattered
over the Forest. One of the largest is Spirogyra nitida,
and about as common as any of them ; when in fruit the
zygospores are very large. Spirogyra longata occurs
at High Beach, as well as at Snaresbrook. Spirogyra
porticalis is by no means uncommon, as also Spirogyra
flavescens at High Beach and Wanstead Flats. Species
with thinner and more delicate threads, such as
Spirogyra Weberi, at Walthamstow and High Beach,
and Spirogyra tenuissima at the same places. It is to
be regretted that for some of the rarer species, the
special ponds in which they have been found have not
been indicated.
In Zygnema the endochrome is not arranged in spiral
bands, but forms two star-shaped or globose bodies in
each cell. Three species have been found at High
Beach, and these are Zygnema cruciatum, Zygnema
Vaucherii, and Zygnema anomalum, the former also at