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and the Flageliata. 
In the absence of any primitive forms any theory of the 
origin of this group was then simply a matter of speculation, 
but a possible derivation from brown Flagellate organisms was 
suggested as a parallel with the origin of the green Algae. 
Links to substantiate such a line have now been discovered, 
and this theory may be considered as at the present time 
firmly established. It is of the greatest interest to note that 
the intermediate organisms show a striking parallelism in 
grade with those in a similar position on the phylum of the 
Chlorophyceae. 
We have thus a rising series :— 
1. Organisms which are generally admitted to be Flageliata, 
as Synura , Uroglena , and Hydrums. 
2. Phaeocystis , which approaches the border line of the 
Algae. 
3. Phaeococcus and Entodesmis , which correspond to the 
Tetrasporaceae among the green Algae. 
4. Phaeodactylon and SticJwgloea , parallel with the Pleuro- 
coccaceae. 
5. Phaeothamnion corresponding to a very simple type of 
Confervoideae and leading to— 
6. The typical Phaeosporeae which have the unilateral 
swarm-spore and so-called uni- and multilocular sporangia. 
At the present time most of these intermediate groups are 
very imperfectly known, but taken together they seem to form 
a bridge over the gap, which is sufficiently strong to carry this 
hypothesis of the evolution of the Phaeophyceae from Flagel- 
lata quite independently of the evolution of the Chlorophyceae 
and the Heterokontae. 
We will go briefly through some of the points of interest in 
this series of forms. 
It is a general character of this phylum that the chromato- 
phores are brown, and the product of assimilation neither 
starch nor oil, and that the cilia of the motile cells are usually 
unsymmetrical. 
The first group of these forms belongs to the sub-family 
Chrysomonadina of the Chromomonadina. Here we find 
