the group,
substituted the name _Myxomycetes_. In the same year Wallroth adopted
the same designation, but strangely confused the limitations of the
group he named. Wallroth seems to have thought _Myxomycetes_ a synonym
for _Gasteromycetes_ Fries. In 1858 DeBary applied the title _Mycetozoa_
to a group which included the then lately discovered _Acrasieae_ with
the true slime-moulds, both endosporous and exosporous. For all except
the _Acrasieae_ DeBary retained the old appellation, Myxomycetes.
Rostafinski adopted DeBary's general name, but changed its application.
As it has been shown, since DeBary's time, that the _Acrasieae_[3] have
no true plasmodium, and are therefore not properly, or at least not
necessarily, associated with the slime-moulds, there appears no
necessity for the term _Mycetozoa_, and the question lies between
_Myxogastres_ and _Myxomycetes_. Of these two names the former, as we
have seen, has undoubted priority, but only as applied to the
endosporous species. The same thing was true of Link's designation until
DeBary redefined it, but having been taken up by DeBary, redefined and
correctly applied, Myxomycetes (Link) DeBary must remain the undisputed
title for all true slime-moulds, endosporous and exosporous alike.

In arranging the larger divisions of the group the scheme of Rostafinski
has been somewhat modified in order to give expression to what the
present author deems a more natural sequence of species. The highest
expression of myxomycetan fructification is doubtless the isolated
sporangium with its capillitium. This is reached by successive
differentiations from the simple plasmodium. The aethalium may be
esteemed in some instances a case of degeneration, in others of arrested
development. In any event in the present arrangement, aethalioid forms
are first disposed of, leaving the sporangiate species to follow from
plasmodiocarpous as directly as may be.

The artificial keys herewith presented proceed on the same plan and are
to be taken, as such keys always are, not as definitive in any case, but
simply as an aid to help the student more speedily to reach a probably
satisfactory description.

FOOTNOTES:

[1] _The North American Slime Moulds_, 1899.

[2] Schrader, _Nova Plantarum Genera_, 1797, pp. vi-vii.

[3] Cf. Edgar W. Olive, _Monograph of the Acrasieae_; Boston, 1902.

PREFACE TO THE SECOND EDITION

The first edition of this little book having been exhausted long ago,