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OF SOUTH AUSTRALIA. 127 
Pacific. Here it is found at all seasons of the year. It grows in ribbons 
at the edge of rough water, lying plastered together on flat surfaces of the 
rocks when the sea recedes, the fronds covering one another and so retaining 
a certain amount of moisture when exposed to the sun and air. The colour 
is an olive-fawn, very dark when seen in mass and becoming more or less 
red or purple as the plants are dried. The young plants are narrow and 
simple. The adult become broad, laciniate with undulate margins, mostly 
10 cm. to 15 cm. high. Antheridia are formed from most cells in a male 
plant, the frond becoming paler and thicker as the sperms develop from the 
mother cells. Bach of these has been observed to form 64, or sometimes 128 
colourless sperm cells. The egg cells (carpogonia) are without a trieho- 
gyne. When fertilized each divides into eight spores without the aid of an 
auxiliary cell. 
Fig. 6 . — Porphyra umbilicalis : a, habit of a plant, x 
J; b, portion of a blade, showing 
cell arrangement, chromatophores, and 
carposporangium arrangement, x 160; c, 
portion of blade, showing spermatangium 
formation at the margin, x 160. (After 
Taylor.) 
The monosporangia (gonidia) each form a single monospore. Very little 
is known about them, but they seem to take the place of the tetrasporangia 
of the higher Red Algae. 
Porphyra furnishes a plentiful supply of food to people in quite distant 
regions of the globe. In Scotland, Wales, and Ireland it is regarded as a 
delicacy. The name given to it is Laver, and the baking of Laver bread is 
not unknown even in Sydney. In Honolulu, China, and Japan systematic 
use is made of Porphyra. A very tender rosy species P. tenera , is actually 
cultivated on a large scale in Japan. Tilden states that in 1901 the culti- 
vated sea-bottom in Japan extended to 2,242 acres. She quotes Hugh M. 
Smith, who has written a full description of the industry in Tokio Bay. 
In 1903 the yield was valued at 300,000 dollars. The number of families 
engaged in the work was estimated at 4,395. Smith’s work was published 
in 1905. 
