I nter-Relationships of Protista and Primitive Fungi. 95 
Myxomycetes (in the wide sense) and Chytridiales. The working 
theory adopted as affording a plausible clue to the inter-relation¬ 
ships of these groups, or at any rate a thread upon which to hang 
the scattered facts here brought together, is that these forms have 
had a common origin in certain Flagellata which may with equally 
great or little plausibility be regarded also as the ancestors of the 
coloured or algal series which have already been dealt with. As was 
pointed out in considering these algal series, we find at the base of 
almost every line along the Green and Brown organisms a “ masti- 
gamceboid ” form—a form with a naked pear-shaped body having 
at the pointed end one or more flagella while also capable of 
locomotion and holozoic ingestion by means of psuedopodia put out 
usually from the blunt posterior end; such forms are Chloramceba , 
Chrysamceba, Hywenowonas, Ochromoncis and Wysotzkia. It was 
also pointed out that apart from their possession of chromatophores 
these forms show a striking resemblance to Mastigamceba and other 
colourless Flagellata usually placed in the groups Pantostomatineae 
and Protomastiginese—a resemblance which in the case of Chryso- 
monads especially extends to such details as the method of cyst- 
formation and which suggests the view that such Protomastiginean 
forms as Monas, Oikonionas, etc., may have been derived from 
Chrysomonads in the same way that such genera as Polytoma are 
regarded as colourless derivatives of Chlamydomonads, etc. This 
suggestion, followed out to its logical conclusion, involves the 
assumption that all the colourless Flagellata have arisen from 
coloured forms, an assumption which can only he justified if regarded 
as a purely speculative working theory. It was also suggested 
that these various mastigamoeboid coloured forms, each apparently 
standing at the root of a remarkably complete ascending series of 
forms of which some at any rate lead definitely to algal types, might 
have arisen from a hypothetical Multicilia-Uke ancestor in which 
the spherical naked body possessed numerous uniformly distributed 
flagella and the power of putting out pseudopodia from any point as 
in Multicilia, but which differed from this colourless Flagellata 
genus in being an autotrophic form. 
There appears to be a fairly general concensus of opinion 
among zoological writers that the Flagellata, and of these the group 
(Pantostomatinese) which includes Multicilia and Mastigamceba and 
their allies, may be regarded as the most primitive group of Protozoa 
and as representing the common ancestors of all the classes of 
unicellular animals. Various recent botanical writers on the 
Myxomycetes (Mycetozoa) and allied groups such as certain 
Chytridiales, the Acrasieae, etc., have referred—usually in a vague 
and general manner—to the possibility of relationships between 
these groups and certain groups of Protozoa, such as the Sarcodina, 
Heliozoa and Sporozoa; hence in this review these Protozoan 
groups will be considered in some detail in so far as their characters 
appear to throw light upon the relationships of the Myxomycetes, 
etc. As might be expected, it is the lower members of the various 
groups that are of interest in this connexion. 
II.— Classification of the Protozoa. 
Four main groups of Protozoa are now generally recognised— 
Sarcodina, Flagellata, Sporozoa and Infusoria. The Sarcodina are 
