686 Blackman .— The Primitive Algae 
significant of the Flagellate origin that nearly all of the 
primitive forms inhabit fresh water. 
The gaps in the series that we have gone through are too 
large to allow very precise phylogenetic speculation, but the 
schema on pp. 684, 685 embodies the views of Scherffel, 
Lagerheim and Bohlin. 
The origin of the third great group of Algae, the Rhodo- 
phyceae, is still a vexed question which is discussed at some 
length by Schmitz ; see Hauptfleisch (’ 94 ). Until recently no 
Flagellate with the characteristic Floridean red colour had 
been described, so that such an origin, parallel with that of the 
Chlorophyceae and Phaeophyceae, seemed out of the question. 
Karsten (’ 98 ) figures such a marine organism. Rhodomonas 
(Fig. 14) with two cilia and a large single indented chroma- 
tophore of true Floridean red colour. Its life-history is at 
present unknown. The occurrence of a typical Flagellate with 
this pigment just suggests the possibility of such an origin of the 
Bangiales and Florideae, but no more than this can be said. 
Postscript. 
Since these sections on the lower Algae and the Flagellata 
were written there has appeared a new treatise on the Flagellata 
by Senn (’ 00 ), who has worked under Klebs. This comes as 
an addition to the original scheme of Engler and PrantPs 
‘ Pflanzenfamilien,’ and clearly enforces one of the main argu¬ 
ments of this paper, viz. that without studying this group, 
though it is admitted not to be a plant-group, a clear com¬ 
prehension of the relations of the primitive Algae cannot be 
obtained. 
The arrangement in this excellent work follows that pro¬ 
posed by Klebs (’ 92 ) for the pigmented forms, but some further 
useful subdivisions are carried out for the colourless forms 
furthest removed from the vegetal type. 
Senn hesitates to accept the suggested relation of the Con- 
fervales with the Flagellate Vacuolaria on the grounds that the 
latter is too highly differentiated, but the simple hypothesis of 
a common ancestor destroys none of the interest of the theory. 
