94 F. Cavers. 
THE INTER-RELATIONSHIPS OF PROTISTA AND 
PRIMITIVE FUNGI. 
By F. Cavers. 
I.—Introduction. 
I N preparing the summarised compilation of literature on the 
primitive Algae and on the Flagellata from which these have 
probably arisen, with an outline of the possible relationships 
between these organisms, which appeared in this journal some time 
ago (Cavers, 1913), it was at first intended to take a wider survey 
of the relations between the Protista and primitive algal and fungal 
forms as a whole. This would have been the more logical course, 
but it appeared better at that time to limit the scope of the 
compilation in order to deal more fully with the extensive additions 
made during recent years to our knowledge of the “ algal ” Flagellata 
and transitional forms, in particular those belonging to the Brown 
Series which have been so thoroughly worked out by Pascher, 
Scherffel and others whose labours have resulted in the discovery 
of many new forms, and may be said to have completely established 
the view that both Green and Brown Algae are traceable by almost 
imperceptible gradations through an astonishing complete series 
of connecting forms to certain types of Flagellata from which they 
have probably originated. 
As was pointed out in dealing with the “ algal ” series we are 
not justified in assuming that autotrophic pigmented organisms 
necessarily appeared in advance of, and gave rise to, forms devoid 
of light-absorbing pigments; indeed the argument, from general 
considerations, that organisms devoid of such definite cell-organs as 
chroinatophores must have preceded in evolution those possessing 
them is strongly backed up by the knowledge that among the 
Bacteria we find many different processes of metabolism some of 
which cannot be confined within arbitrary definitions such as are 
implied by terms like “ holophytic,” “ saprophytic,” and so on, and 
that the conception of “ prototrophic ” may well be applied to those 
Bacteria which appear to have the power of fixing carbon dioxide 
as well as free nitrogen. Since the affinities of the Bacteria and of 
the Cyanophyceae (Myxophyceae) can hardly be said to have been 
cleared up to any appreciable extent by recent work, the former will 
be excluded from the present survey of the colourless organisms just 
as the latter were from that of the coloured organisms, though it 
may be remarked in passing that the Bacteria are in all probability 
a polyphyletic and unnatural group, for while some (the majority) 
of its members show fairly obvious affinities with the Flagellata 
others appear to approach in certain respects the Sarcodina among 
the Protozoa, and others again should probably be united with the 
higher Fungi. The curious and interesting group of Myxobacteriales 
is also excluded from the present review on the ground that there 
appears to be little or nothing to justify the view suggested by some 
writers that they are related to the Myxomycetes (Mycetozoa). 
We are therefore mainly concerned here with the colourless 
non-autotrophic organisms comprised in the Flagellata, Protozoa, 
