OF SOUTH AUSTRALIA. 
19 
CHLOROPHYCEAE. (Green Seaweeds.) 
Algae containing in their cells pure chlorophyll, located in definite bodies 
(chlorophores), and in consequence typically green. 
There are unicellular and multicellular forms. The unicellular may be 
quite simple, very small single cells, with a single nucleus, or may be 
multinucleate and form a highly elaborate thallus or frond. The multi- 
cellular consist of cells which grow in a single row to form a simple or 
branched filament, or of cells which are in addition united laterally and 
so form a membrane or tube. 
Multiplication is effected non-sexually or sexually. Non-sexual multipli- 
cation (propagation) occurs by the division of the whole plant, if it 
consists of a single small cell, or of a part of the plant, if it be a complex 
of cells. The separated divisions do not conjugate. If active they are 
termed Zoogonidia or Zoospores, but if persistently inactive they are 
termed Aplano-spores or Cysts. 
Sexual multiplication (generation) consists in the formation of an 
immobile cell (zygote, oospore) by the union of sexual cells (gametes) 
which lack a cell wall. There are four varieties of such union: — 
1. Union of equal quite similar gametes which are ciliated and active : 
Isogamous reproduction. 
2. Union of mobile antherozoids with an immobile oosphere : Oogamous 
reproduction. 
3. Union of immobile antherozoids (Pollinidia) with an immobile 
oosphere: Oogamous reproduction. 
4. Union of two large immobile gametes : Conjugation. 
The last occurs in the freshwater Zygnemaceae, Zygnema and 
Spirogyra, and the Desmids. 
The great majority of the Green Algae flourish in fresh waters, but 
representatives of most families (excluding those of the Conjugatae) are 
met with in the seas. Minute free-floating pelagic forms abound in the 
plankton near the surface of the great oceans. The attached forms live 
mostly in quite shallow waters and between tide marks. In his monumental 
work, the Sylloge Algarum, in the volume published in 1895, De Toni, the 
great Italian phycologist, enumerated nearly 3,000 species of marine and 
freshwater Chlorophyceae as then known in the world’s flora. So far only 
130 marine species have been recorded from Australia; of these only 29 
have been found in South Australia; these belong to the two Orders 
Confervoideae and Siphoneae. The former are multicellular and the latter 
unicellular. The Siphoneae are well represented in the warmer waters of 
the coral islands and the Great Barrier Reef. 
