l82 THE ESSEX NATURALIST.
mends a shovel, but as it is not possible to use such a tool in.
Epping Forest or in other woodlands to which there is access,
different means must be employed. It has been possible to collect
mycorrhiza with the aid of a small trowel or scout's knife from
those trees that grow on a bank which slopes rapidly in one
direction, for in such situations roots are often conveniently
near the surface.
On holding up to the light a bottle or tube containing fungus-
root which has been rinsed in water, a large number of hyphal
threads can be easily seen by the aid of a hand-lens of a magnify-
ing power of X6 or X8. Besides the attenuated threads, many
others of greater thickness and broad bands of fungoid substance
are visible. The humus in which mycorrhiza flourish is thoroughly
permeated with the hyphae of many kinds of fungi.
Hyphae attached to fungus-roots vary in colour from white
through yellow to brown, and the mycorrhiza which they form
are, when young, of a corresponding shade.
The number of fungi that are known to form mycorrhiza
is small. Peyronel5 states that "The total number of Basidio-
mycetes forming fungus-roots is a little less than twenty."
He especially mentions Amanita muscaria, Lactarius necator
Pers (= L. turpis (Weinm), Fr.), Boletus scaber and Scleroderma
vulgare as fungi which form mycorrhiza on the silver birch,
Boletus chrysenteron and Scleroderma vulgare as forming them on
beech, and Boletus rufus (Schaeff) Quel. (= B. versipellis Fr.)
on the aspen. All of these, with the exception of the last-named,
are quite common in Epping Forest. They are exhibited on the
tables at every foray. Noack6 found five species of agarics
that were apparently mycorrhiza producers on the forest trees
in the locality where he made his observations; two were
Tricholomas and three Cortinarii.
Mycorrhiza are not suitable for herbarium purposes, but
they can be preserved satisfactorily in formalin.
After reaching home my gatherings have been washed in
slowly running water. This removes loose soil and decaying
vegetation without unduly breaking hyphae from the points
of attachment.
For further investigation microtome sections are necessary.
5. Peyronel, M. Beniamino. Bull. Trimes. de la Soc. Mycol. de France.
6. Noack, R., Ueber Mycorhizenbildende Pilze, Bot. Zeit., 47, p. 389, 1889.