true, that
all parts of these fungi were seldom phosphorescent.

The luminous phenomenon in question is without doubt more complicated
than it appears, and the causes to which we attribute it are certainly
powerfully modified by the general character of the objects in which
they reside. Most of the German botanists give this explanation,
others suppose that it forms at first or during its continuance a
special matter, in which the luminous property resides; this matter,
which is said to be mucilaginous in the luminous wood, appears to be
in the _Rhizomorpha_ only a kind of chemical combination between the
membrane and some gummy substance which they contain. Notwithstanding
this opinion, I am assured that all external mucous matter was
completely absent from the _Agaricus olearius_, and I neither
discovered it upon the branches of _Rhizomorpha subterranea_ nor upon
the dead leaves which I have seen phosphorescent; in all these objects
the luminous surfaces were nothing else than their proper tissue.

It may be remarked here that the so-called species of _Rhizomorpha_
are imperfect fungi, being entirely devoid of fructification,
consisting in fact only of a vegetative system--a sort of compact
mycelium--(probably of species of _Xylaria_) with some affinity to
_Sclerotium_.

Recently an extraordinary instance of luminosity was recorded as
occurring in our own country.[H] "A quantity of wood had been
purchased in a neighbouring parish, which was dragged up a very steep
hill to its destination. Amongst them was a log of larch or spruce, it
is not quite certain which, 24 feet long and a foot in diameter. Some
young friends happened to pass up the hill at night, and were
surprised to find the road scattered with luminous patches, which,
when more closely examined, proved to be portions of bark or little
fragments of wood. Following the track, they came to a blaze of white
light which was perfectly surprising. On examination, it appeared that
the whole of the inside of the bark of the log was covered with a
white byssoid mycelium of a peculiarly strong smell, but unfortunately
in such a state that the perfect form could not be ascertained. This
was luminous, but the light was by no means so bright as in those
parts of the wood where the spawn had penetrated more deeply, and
where it was so intense that the roughest treatment scarcely seemed to
check it. If any attempt was made to rub off the luminous matter it
only shone