I nter-Relationships of Protista and Primitive Fungi 277 
In Schroter’s classification in Engler and Prantl (1897) the 
Myxomycetes (Mycetozoa) are divided into three groups—Acrasieae, 
Phytomyxinefe and Myxogasteres. Lotsy (1907) slightly rearranges 
this scheme by adding to the Acrasieae the small family Labyrin- 
thuleae (Labyrinthula and CJilamydomyxa), thus restoring Zopf’s 
group Sorophoreae (distinguished by having a “ false ” or aggregation 
plasmodium in which the amoebae do not become fused together) 
and applying the name Myxogasteres to the two remaining groups, 
in which the amoebae fuse completely in plasmodium formation. He 
divides the Myxogasteres into Eumyxogasteres (Myxomycetes in the 
narrower and more usual sense) which have, and Plasmodio- 
phoraceae (Phytomyxineae) which have not, a definite fruit-body. 
Lotsy, like various other writers, holds that the differences between 
these two groups are attributable to the parasitic mode of life of 
the Plasmodiophoraceae, which are regarded as derived from the 
Eumyxogasteres, a view recently supported by Pavillard (1910) in his 
invaluable critical review of the literature of vegetable protistology. 
However, various considerations point to the conclusion that the 
Plasmodiophoraceae have more probably originated independently of 
the Myxomycetes proper, though being closely related to that group, 
and that both are related to the Chytridiales and to the Protozoa 
(especially to the Sarcodina and Sporozoa). The Acrasiales 
(including the Acrasieae together with certain recently described 
forms which may be at least provisionally placed near them) stand 
somewhat apart from the Plasmodiophorales (the name adopted here 
to include not only the Plasmodiophoraceae but also some forms 
apparently best placed near this family), Myxomycetes and Chytridi¬ 
ales in not showing a flagellate phase and in the different type of 
vegetative body, but in any case the origin of the Acrasiales is 
doubtless to be sought in the Proteomyxa, not far from that of the 
other three groups of “ primitive fungi.” 
Since, as we shall see later, there is much to be said for the 
view that the so-called “algal fungi” (Phycomycetes) are far more 
probably derived from the Chytridiales than from the green algae, it 
would appear reasonable to extend the name Archimycetes, some¬ 
times used as a synonym for Chytridiales, to include the whole of 
the lower fungi, which would then fall into the six divisions 
Chytridiales, Myxomycetes, Plasmodiophorales, Acrasiales, Zygomy¬ 
cetes and Oomycetes. 
Beginning with the Chytridiales, we take as a basis for our 
discussion of this group Schroter’s account in Engler and Prantl, 
as no compilation of equal scope has appeared since this was 
published, though in the intervening twenty years a very large 
amount of work has been done on these organisms. Schroter 
placed the Chytridinese, together with the Ancylistineae, in a division 
of the Oomycetes characterised by having the mycelium absent or 
feebly developed, as compared with the well-developed mycelium of 
the remaining Phycomycetes. In Chytridinese the fructification is 
said to consist of a solitary sporangium or of a sorus formed by 
division, while in Ancylistineae the fructification is divided by cross¬ 
walls into a chain of cells. The Chytridineae are divided into six 
families, characterised as follows :—A. Resting sporangium formed 
asexually, or rarely by copulation of zoospores, a. Mycelium absent. 
I. Sporangia solitary.— Olpidiacece. II. Sporangia aggregated in 
