8 WORK IN THE FIELD AMONGST THE FUNGI.
infest and destroy our crops, and thus compel attention to the
invaders, not from choice, but from self interest.
The solving of puzzles in this branch of mycology has been
proceeding gradually, but I think surely, in the past year.
Professor Perceval's researches on "silver leaf" of fruit trees
appears to be promising a successful issue. The causes affecting
"club root" are engaging attention. The life history of many
parasites are better elucidated, and faith in the use of fungi-
cides gains strength day by day.
I should call your attention, as a practical matter, to the
recent publication by my friend and pupil, Mr. George Massee,
of a useful volume, entitled European Fungus Flora, Agaricaceae,
which replaces, as far as it goes, the Clavis, published some
years ago, by myself, in conjunction with Dr. Quelet. The
present volume includes only the Agaricacece, but it contains all
the species hitherto known as occurring in Europe, with a
special indication of those found in Britain. The Clavis included
1,943 species, of which 939 were given as British. The present
work includes 2,750 species, of which 1,553 are British. The
letterpress is in English, whereas that of the Clavis was in Latin.
The descriptions, although compact, are longer and more com-
plete than those of the Clavis, adding, in most cases, the dimen-
sions of the spores. The classification is, for the most part,
founded on that of Saccardo's Sylloge, and the construction of
the work is evidently based upon the desire to make it a handy
field book for the determination of species, as well as a com-
pendium for home use. I can congratulate the author upon a
successful achievement of his desire, and all mycologists who
may be fortunate enough to possess it, of a valuable addition to
the mycological literature of the year.
I also may be permitted, with some reserve, to refer to
another publication, in which I am myself interested. Notwith-
standing the valuable contributions to the subject of Plant
Diseases by Mr. Massee and Professor Marshall Ward, it has
long been felt that what is wanted in this country is a full
enumeration of plant diseases of fungus origin, illustrated as
much as possible by coloured figures, so as to assist the cultivator
and the amateur. All efforts to secure a publisher for such a
work having failed, the Royal Horticultural Society was appealed
to, and ultimately arrangements have been made for issuing this