equire to be discarded. This
is especially the case with _Boletus luridus_[C] and _Boletus
Satanas_,[D] two species which have the under surface or orifice of
the pores of a vermilion or blood-red colour.

Not only are species which are known to be poisonous to be avoided,
but discretion should be used in eating recognized good species. Fungi
undergo chemical changes so rapidly that even the cultivated mushroom
may cause inconvenience if kept so long after being gathered as to
undergo chemical change. It is not enough that they should be of a
good kind, but also fresh. The employment of plenty of salt in their
preparation is calculated very much to neutralize any deleterious
property. Salt, pepper, and vinegar are much more freely employed
abroad in preparing fungi than with us, and with manifest advantage.

It is undoubtedly true that fungi exert an important influence in
skin diseases. This seems to be admitted on all hands by medical
men,[E] however much they may differ on the question of the extent to
which they are the cause or consequence of disease. Facts generally
seem to bear out the opinion that a great number of skin diseases
are aggravated, and even produced, by fungi. Robin[F] insists that a
peculiar soil is necessary, and Dr. Fox says it is usually taught
that tuberculous, scrofulous, and dirty people furnish the best
nidus. It is scarcely necessary to enumerate all these diseases,
with which medical men are familiar, but simply to indicate a few.
There is favus or scall-head, called also "porrigo," which has its
primary seat in the hair follicles. Plica polonica, which is
endemic in Russia, is almost cosmopolitan. Then there is Tinea
tonsurans, Alopecia, Sycosis, &c., and in India a more deeply-seated
disease, the Madura Foot, has been traced to the ravages of a fungus
described under the name of _Chionyphe Carteri_.[G] It is probable
that the application of different names to the very often imperfect
forms of fungi which are associated with different diseases is not
scientifically tenable. Perhaps one or two common moulds, such as
_Aspergillus_ or _Penicillium_, lie at the base of the majority, but
this is of little importance here, and does not affect the general
principle that some skin diseases are due to fungi.

Whilst admitting that there are such diseases, it must be understood
that diseases have been attributed to fungi as a primary cause, when
the evidence does not warrant such a conclusion. D