INTRODUCTION. 
The Algae belong to the plant group Thallophyta, the group which 
contains those organisms which possess vegetative bodies undifferentiated 
into root, stem, leaves, etc. They range in form from the simplest unicells, 
to the collection of unicells in colonies, thence to multicellular, filamentous 
organis m s and types in which the filaments become compacted in a 
gelantinous matrix to form a thallus, through to the highest thalloid forms 
in which the organization becomes more or less parenchymatous. The group 
Thallophyta includes two very large sub-groups — the Algae and the Fungi. 
These are differentiated from one another by their mode of nutrition, the 
former possessing a photosynthetic apparatus and thus being able to syn- 
thesize organic carbon compounds from simpler inorganic sources, while 
the latter are saprophytes or parasites requiring organic compounds in a 
ready-made form. 
The Algae are divided by F. E. Fritsch, in his “Structure and Repro- 
duction of the Algae” (1935) into 11 classes. The four listed below are 
the most important in Australian waters, and although some of the others 
are undoubtedly present they are otherwise quite unknown. This applies 
particularly to the large group of the Diatoms or Bacillariophyceae. 
Chloropiiyceae (Green algae). — Chromatophores grass-green in 
colour, containing the same four pigments (two green, two 
yellow) as in higher plants. Reproductive cells motile, ranging 
from isogamy to oogamy. The class is more widely represented 
in fresh than in salt water. 
Phaeophyceae (Brown algae). — Brown colour is due to the brown 
pigment fucoxanthin masking the chlorophyll in the plastids. 
Thalli various, ranging from simple to highly developed tissue 
systems, some of which may attain gigantic proportions. Gametes 
ciliated with the cilia inserted at the anterior end of the pyriform 
zooid, and unequal in length. 
Rhodophyceae (Red algae). — Colour is due to the rose-pink pigment 
phycoerythrin in the chromatophores. Sexual cells typically non- 
motile. Carbohydrate storage product is Floridean starch 
replacing true starch. Thalli very variable in form and 
organization. 
Cyanophyceae (Blue-green algae). — Cells simple, with rudimentary 
nuclei, no proper chromatophore. Characterized by the pigment 
phycocyanin, giving the cells a blue-green colour. No motile 
stages known. No sexual reproduction, division occurring 
vegetatively. They range from unicells to aggregate — filamentous 
forms. Abundant in fresh waters, and common in the sea, though 
little is known of the Australian forms. 
The algal flora of any natural body of fresh-water is predominantly a 
mixture of Greens, Blue-greens or Yellow-greens; the Browns are not 
represented, while among the Reds, only a very few of the more primitive 
types are known from such localities. In Australia an example of such 
JiAIIQNAL HERBARIUM OF VICTORIA 
