166
A. D. BONEY
about mean sea level, so that there will be daily periods of exposure to
air. This exposure time will vary from month to month, (e.g. daytime
exposure is longer from March to April than from October to December,
whereas nightime exposure is long from November to March and short
during May and June). At the time of year when " hibi " are spread
(September) they are exposed to the air for daily periods of 4-44 h in
the day and 6 h at night ; during the main harvesting period (DecemberJanuary) the daytime exposure is 2 h and the nightly period 84 h. At
the end of the season of cultivation the " hibi " are exposed for 84 h by
day and for 2 h at night (Kurogi, 1961). Studies on the metabolism of
Porphyra tenera when immersed in water of Werent salinities, at
different temperatures and after drying have been reported (Ogate,
1963; Ogata and Matsui, 1963). Changes in respiration rate were
observed with increased temperatures, and lowering of the salinity
resulted in an increase in the rate. Measurable respiration was observed
with plants left uncovered by the sea.
3. Cultivated Porphyra species in Japan and China
Kurogi (1961) described five species of Porphyra which are cultivated
in Japan, viz. :
Porphyra tenera, P. kuniedai, P. angusta, P. yemewis, and P.
pseud olinearis .
Numerous studies have been carried out on the Conchocelis-phases
of these five species, and this work will be considered separately (see
p. 177 et seq.).
Porphyra tenera. The type material of this species was described by
Kjellman in 1897 from samples of the dried laver " sheets " used as
food (Segi, 1959). Two types of frond were described, those of a linear
form and those which were rounded. A type specimen based on a commercial product is more than usually confusing, and no doubt accounts
for the variability of form attributed to the species by several authors.
Porphyra tenera appears to be the most commonly cultivated laver in
Japan and China. Detailed accounts of this species and its cultivation
in Japan have been given by Kurogi (1961, 1963a, b ) ; it is a plant
characteristic of the " inner " seas, (e.g. those almost surrounded by
land), and shows a relatively short annual growth period.
Frond shape vanes from linear to oval, with a tendency to become
much broader with age, and to widen appreciably when grown in
shallow seas rich in nutrients. The apex of the frond is generally obtuse
and the base cuneate, rounded, and sometimes cordate. Plants which
appear in the early part of the growth period are noticeably broader
than those which develop later. Frond lengths range up to 25 cm, and
A. D. BONEY
about mean sea level, so that there will be daily periods of exposure to
air. This exposure time will vary from month to month, (e.g. daytime
exposure is longer from March to April than from October to December,
whereas nightime exposure is long from November to March and short
during May and June). At the time of year when " hibi " are spread
(September) they are exposed to the air for daily periods of 4-44 h in
the day and 6 h at night ; during the main harvesting period (DecemberJanuary) the daytime exposure is 2 h and the nightly period 84 h. At
the end of the season of cultivation the " hibi " are exposed for 84 h by
day and for 2 h at night (Kurogi, 1961). Studies on the metabolism of
Porphyra tenera when immersed in water of Werent salinities, at
different temperatures and after drying have been reported (Ogate,
1963; Ogata and Matsui, 1963). Changes in respiration rate were
observed with increased temperatures, and lowering of the salinity
resulted in an increase in the rate. Measurable respiration was observed
with plants left uncovered by the sea.
3. Cultivated Porphyra species in Japan and China
Kurogi (1961) described five species of Porphyra which are cultivated
in Japan, viz. :
Porphyra tenera, P. kuniedai, P. angusta, P. yemewis, and P.
pseud olinearis .
Numerous studies have been carried out on the Conchocelis-phases
of these five species, and this work will be considered separately (see
p. 177 et seq.).
Porphyra tenera. The type material of this species was described by
Kjellman in 1897 from samples of the dried laver " sheets " used as
food (Segi, 1959). Two types of frond were described, those of a linear
form and those which were rounded. A type specimen based on a commercial product is more than usually confusing, and no doubt accounts
for the variability of form attributed to the species by several authors.
Porphyra tenera appears to be the most commonly cultivated laver in
Japan and China. Detailed accounts of this species and its cultivation
in Japan have been given by Kurogi (1961, 1963a, b ) ; it is a plant
characteristic of the " inner " seas, (e.g. those almost surrounded by
land), and shows a relatively short annual growth period.
Frond shape vanes from linear to oval, with a tendency to become
much broader with age, and to widen appreciably when grown in
shallow seas rich in nutrients. The apex of the frond is generally obtuse
and the base cuneate, rounded, and sometimes cordate. Plants which
appear in the early part of the growth period are noticeably broader
than those which develop later. Frond lengths range up to 25 cm, and