onditions of mould. It may well occasion some surprise that
fungi should be found growing within cavities wholly excluded from the
external air, as in the hollow of filberts, and the harder shelled
nuts of _Guilandina_, in the cavities of the fruit of tomato, or in
the interior of an egg. It is scarcely less extraordinary that
_Hypocrea inclusa_ should flourish in the interior of a kind of
truffle.

From the above it will be concluded that the habitats of fungi are
exceedingly variable, that they may be regarded as almost universal
wherever decaying vegetable matter is found, and that under some
conditions animal substances, especially of vegetable feeders, such as
insects, furnish a pabulum for their development.

A very curious and interesting inquiry presents itself to our minds,
which is intimately related to this subject of the habitats of fungi.
It shapes itself into a sort of "puzzle for the curious," but at the
same time one not unprofitable to think about. How is the occurrence
of new and before unknown forms to be accounted for in a case like the
following?[Q]

It was our fortune--good fortune as far as this investigation was
concerned--to have a portion of wall in our dwelling persistently damp
for some months. It was close to a cistern which had become leaky. The
wall was papered with "marbled" paper, and varnished. At first there
was for some time nothing worthy of observation, except a damp
wall--decidedly damp, discoloured, but not by any means mouldy. At
length, and rather suddenly, patches of mould, sometimes two or three
inches in diameter, made their appearance. These were at first of a
snowy whiteness, cottony and dense, just like large tufts of cotton
wool, of considerable expansion, but of miniature elevation. They
projected from the paper scarcely a quarter of an inch. In the course
of a few weeks the colour of the tufts became less pure, tinged with
an ochraceous hue, and resembling wool rather than cotton, less
beautiful to the naked eye, or under a lens, and more entangled. Soon
after this darker patches made their appearance, smaller, dark olive,
and mixed with, or close to, the woolly tufts; and ultimately similar
spots of a dendritic character either succeeded the olive patches, or
were independently formed. Finally, little black balls, like small pin
heads, or grains of gunpowder, were found scattered about the damp
spots. All this mouldy forest was more than six months under constant
o