152
A. D. BONEY
Growth and environmental tolerances of the gametophytes. Studies
on the growth and environmental tolerances of several species of
Laminaria are available. Since the earlier work of Ikari (1921) ; Ueda
(1929) ; Schreiber (1930) ; Harries (1932) and Carter (1935) more recent
reports are available from Parke (1948) ; Walker and Smith (1948) ;
Tseng, Sun and Wu (1955a, 1957); Nishibayashi and Inoh (1956);
Burrows (1961) ; Hasegawa (1962) ; Sundene (1958, 1962) and Kain
(1963).
The initial development of the gametophytes of Laminuria and
related species appears to be much the same. Zoospores liberated from
superficial zoosporangia on the blade of the sporophyte settle on a
substrate, round-off and put out a germ-tube into which the cell
contents pass, and from which the filamentous gametophytes are
formed. Equal numbers of male and female gametophytes develop ; the
male plants being invariably filamentous, whereas the female plants
are either single celled, or may be filamentous. Filamentous female
gametophytes tend to be more resistant, and are perennial.
The zoospores are planktonic during the time immediately prior to
settlement, and Kain (1963) made observations on the time for which
the zoospores remained motile. At 17°C the settlement rate was much
faster than at lO"C, but it is possible for spores to remain non-motile for
several days in suspension, and to commence development whilst still
planktonic. Spores were found to be capable of surviving fairly protracted periods in the dark at 5", 10" and 17°C.
The greater importance of temperature, light and salinity. Gametophytes of L. religioea are viable between 2"-17"C, but produce
gametes between 6"-12°C ; gametophytes of L. sacchurina grow well in
the temperature range 5"-1O"C, and those of both L. sacchrinu and
L. hyperborea were observed to produce gametes when the temperature
was suddenly lowered to 2"-4°C (Schreiber, 1930), whereas Parke (1948)
obtained gametes from gametophytes of L. saccharina at 19°C. Gametophytes of L. digitata were grown by Sundene (1958) at temperatures
between 5"-13°C and Kain (1963) observed survival and growth of
gametophytes of L. hyperborea between 5"-19"C, and survival at
20°C and above. Ripe oogonia were not obtained above 19°C. Tseng
et al. (1957) found 10°C as the optimum temperature for growth of the
gametophytes of L. japonica. Wang and Hsiieh (1969) observed that
Laminaria plants kept through the summer in a culture room at low
temperature took some 2-3 months between release of spores and
appearance of sporophytes 1-2 cm in length.
A number of studies have been made on the influence of light on
gametophyte development and fertility, although in many instances
A. D. BONEY
Growth and environmental tolerances of the gametophytes. Studies
on the growth and environmental tolerances of several species of
Laminaria are available. Since the earlier work of Ikari (1921) ; Ueda
(1929) ; Schreiber (1930) ; Harries (1932) and Carter (1935) more recent
reports are available from Parke (1948) ; Walker and Smith (1948) ;
Tseng, Sun and Wu (1955a, 1957); Nishibayashi and Inoh (1956);
Burrows (1961) ; Hasegawa (1962) ; Sundene (1958, 1962) and Kain
(1963).
The initial development of the gametophytes of Laminuria and
related species appears to be much the same. Zoospores liberated from
superficial zoosporangia on the blade of the sporophyte settle on a
substrate, round-off and put out a germ-tube into which the cell
contents pass, and from which the filamentous gametophytes are
formed. Equal numbers of male and female gametophytes develop ; the
male plants being invariably filamentous, whereas the female plants
are either single celled, or may be filamentous. Filamentous female
gametophytes tend to be more resistant, and are perennial.
The zoospores are planktonic during the time immediately prior to
settlement, and Kain (1963) made observations on the time for which
the zoospores remained motile. At 17°C the settlement rate was much
faster than at lO"C, but it is possible for spores to remain non-motile for
several days in suspension, and to commence development whilst still
planktonic. Spores were found to be capable of surviving fairly protracted periods in the dark at 5", 10" and 17°C.
The greater importance of temperature, light and salinity. Gametophytes of L. religioea are viable between 2"-17"C, but produce
gametes between 6"-12°C ; gametophytes of L. sacchurina grow well in
the temperature range 5"-1O"C, and those of both L. sacchrinu and
L. hyperborea were observed to produce gametes when the temperature
was suddenly lowered to 2"-4°C (Schreiber, 1930), whereas Parke (1948)
obtained gametes from gametophytes of L. saccharina at 19°C. Gametophytes of L. digitata were grown by Sundene (1958) at temperatures
between 5"-13°C and Kain (1963) observed survival and growth of
gametophytes of L. hyperborea between 5"-19"C, and survival at
20°C and above. Ripe oogonia were not obtained above 19°C. Tseng
et al. (1957) found 10°C as the optimum temperature for growth of the
gametophytes of L. japonica. Wang and Hsiieh (1969) observed that
Laminaria plants kept through the summer in a culture room at low
temperature took some 2-3 months between release of spores and
appearance of sporophytes 1-2 cm in length.
A number of studies have been made on the influence of light on
gametophyte development and fertility, although in many instances