OF SOUTH AUSTRALIA. 
59 
The following is a table of the results of five analyses of the gases in the 
floats of Phyllospora coniosa : — 
Percentage Percentage Percentage Percentage 
of Nitrogen. of Oxygen. of Nitrogen. of Oxygen. 
1 86 14 4 82.3 17.7 
2 89.4 10.6 5 83.2 16.8 
3 88.9 11.1 
Thus it will be seen that the proportion of oxygen is less than if air had 
been taken directly into the cavity, and notably much less than in the gas 
content of sea water. Also the carbon dioxide of the latter has disappeared. 
Hence it would appear that the plants, having obtained their gases from 
the sea water, had made use of the carbon dioxide and part of the oxygen 
for purposes of metabolism and had stored up the useless nitrogen and the 
excess of oxygen beyond their requirements to serve the mechanical purpose 
of a float. 
Relation to Adjacent Floras. — The coasts of the south-west and south 
of Western Australia form a region which is occupied by a very definite 
assemblage of marine algae. Similarly the coasts of Victoria and Tasmania, 
which face one another on the opposite sides of Bass Strait, possess a 
marked but different assemblage. The flora of the interlying coasts of 
South Australia possesses elements of both. On the whole, the Bass Strait 
forms predominate, some of them, as Macrocystis, reaching their western 
limit here. Western Australian forms, on the other hand, have spread over 
the shores of the Great Bight, and have invaded the western half of South 
Australia, though they do not reach Victoria. Among the Brown Seaweeds 
the most noticeable of these forms arc Scytothalia, Sargassum cristatum, 
S. fallax, Cystophora racemosa , C. Brownii, C. Grevillei, and Encyothalia. 
Scytothalia from the west and Seirococcus from the east overlap in Victor 
Harbour. 
The Brown Seaweeds are classified in three Orders — Cyclosporinae f 
Tetrasporinae, Phaeozoosporinae. 
Order CYCLOSPORINAE. 
Frond always multicellular of complex structure. Propagation by 
detached fragments. Generation by immobile oospheres fertilised by means 
of bi-ciliated mobile antherozoids, and then transformed into oospores. 
The antheridia and oogonia, often accompanied by hair-like paraphyses, 
are produced in rounded hollows in the frond, with an opening on the 
surface, the conceptacles. 
The Cyclosporinae are divided into four Families — -Sargassaceae, 
Fucaceae, Durvilleaceae, and Spluchnidiaceae. 
