OF SOUTH AUSTRALIA. 
PHAEOPHYCEAE. (Brown Seaweeds.) 
Olive-brown Algae, mostly multicellular, containing in their cells true 
Chlorophyll mingled with and masked by peculiar yellow-brown pigments, 
of which the most general has been termed Phycoxanthin (C 40 H 54 O 6 ). 
The colouring matter is disposed in small definitely limited bodies 
(phaeophores). 
Multiplication is either non-sexual or sexual. The former is effected by 
propagation of detached portions of the plant, or by means of directly 
germinating zoospores; in the Dictyotaceae tetrasporangia occur, single 
cells dividing into four spores capable of independent germination. 1 hese 
resemble the tetrasporangia characteristic of the Red Seaweeds. I he latter, 
or truly sexual, reproduction is by zygotes resulting from the union of 
male and female cells. 
Attachment. — Seaweeds have no roots in the proper sense of the term 
as applied to land plants. They obtain all their food supplies from the 
surrounding sea-water. As, however, the algae of the Littoral Flora are 
fixed throughout life, they provide themselves with organs of attachment. 
These are termed “attachments” or “holdfasts,” and vary considerably in 
form. Some are flat or conical discs which grow closely to the supporting 
substratum of rock or shell, so closely as to preclude the possibility of air 
or water penetrating between holdfast and rock surface. Consequently the 
great pressure of the superincumbent water and atmosphere is sufficient to 
keep the plant in place, despite fairly violent lateral movement of the 
waves. Even Sarcophycns , the Bull Kelp, though its home is on the rocks 
amid surf and breakers, is not often detached, notwithstanding the tremen- 
dous stress caused by the waves pressing on the wide blades of the huge 
frond. The diameter of the disc varies from a few millimetres in the smaller 
forms up to 200 mm. or more in Sarcophycus. In Phyllospora the disc 
is an inch or two in diameter, smooth and concave above, and attached by 
numerous stout radicles which spring from its under-side. In other forms 
the base of the stem sends out stouter branches, each of which terminates 
in an adhesive disc, as in Macrocystis. In yet others, which grow in mud or 
shelly debris, the base gives off many finer fibrils which do not terminate 
in discs, but obtain a foothold in the substratum in much the same way 
as do the fibrous roots of terrestrial grasses. In a very few cases, as in 
Notheia , the rhizoid grows into and becomes continuous with the tissues of 
the host, and the plant would appear to be actually parasitic. 
Structure. — Marine Algae differ from the terrestrial Phanerogams not 
merely in their simpler plan of life but also in consequence of the different 
environment under which they live. They are normally surrounded by sea 
water and their tissues never lack the liquid element. They are not subject 
to droughts. In consequence there is no need of adaptations for 
