232 THE ESSEX NATURALIST.
of course, that, owing to the varying density of the trees and
other causes, the layer of leaves on the ground is broken up into
comparatively small patches interspersed with areas of herbage.
If, however, the smaller patches of dead leaves are of a fairly per-
manent character and merge below into a leaf-mould, they can
quite rightly be deemed as coming under the category of leaf-
carpet.
As regards the origin of the term leaf-carpet I am not clear.
One of our past presidents, the late Mr. Robert Paulson, made
constant use of the term in his researches on mycorrhiza, but
whether he invented it or not I do not know. Anyway, it is a
very convenient term by which to refer to a peculiar and dis-
tinctive biological environment which harbours, as will be seen
later, a very varied microscopic fauna and flora. Certainly from
a natural history point of view it seems preferable to any of the
terms used by soil specialists as it is so much more descriptive.
So far as I can ascertain no systematic work on the organisms
occurring in the leaf-carpet, considered as a distinct biological
environment, has yet been undertaken. There are, to be sure,
numerous records, by zoological and botanical specialists, of
various plant and animal forms having been found among dead
leaves, and a specially large amount of attention has been given
by mycologists to the small fungi found in such places, as also to
the remarkable growths known as mycorrhiza which occur on the
ultimate rootlets of many trees ramifying in the lower part of the
leaf-carpet. Still more to the point are, of course, the records
contained in the works dealing with soils in general and with
forest soils in particular. There are indeed records of numerous
organisms having been found in many kinds of soils, as a reference
to such books as those by Bornebusch (1), France (2), Sandon (9),
and Waksman (12) will clearly show.
It might be surmised that the organisms found in soils
generally would probably be found in the leaf-carpet, and to a
great extent this is certainly true. But there are notable
differences as, for example, the practically complete absence of
coloured algae from the leaf-carpet whereas, in most soils, many
forms of such algae have been recorded. There is obviously also
a similarity in certain respects between the leaf-carpet and the
carpet of mosses which sometimes covers the ground, and many