216 EIGHTH PACIFIC SCIENCE CONGRESS 



however, these methods have not always been effective and further work 

 must be carried out. 



The seasons for spore formation and Hberation have been studied 

 by many authors. In Gelidium Amansii the tetra-spores begin to be 

 shed late in s^^ring when the temperature of the sea water rises to 21°- 

 22°C., and the carpospores at temperatures of 24°-25°C. (3) (5). In 

 Gelidium fastigiatum both spores begin to be shed at about 20°C. (4). 



The liberation of the matured spores occurs almost every afternoon 

 during the season. Sometimes about 100 spores per liter were founded 

 in the sea water near a Gelidium field. The spores fix themselves on 

 the rock surface after having lain in contact with it for about ten 

 minutes (5). 



The germination of spores and their later development into young 

 jDlants have been reported on by Ueda and Katada (6) (11). According 

 to their reports, some of them rise up erectly to form an upright bush, 

 while others form creeping stolons which afterwards emit new upright 

 buds. 



The temperature ranges for normal germination were experiment- 

 ally estimated at 10°-30°C. (optimum 25°-26°C.) in Gelidium Aman- 

 sii (7) and at 10°-25°G. (optimum 16°C.) in Gelidium subfastigia- 

 tum (4). Low salinity (< 1.020) delays the growth of primary rhizoids. 

 Colors of the prevailing light seem to have some effect on the growth 

 of the germ lings of Gelidium. 



In the northern part of Japan negative correlation was found be- 

 tween the yields of Gelidium and the sea water temperature in winter, 

 and Gelidium was not found in the sea where the minimum temperature 

 fell below 2°C. (4). 



Okamura(8), Ueda (9), and Ueda-Katada (6) obtained some data 

 for the growth of Gelidium Amansii in the southern part of Japan. 

 The plants are perennial. They grow very slowly in autumn, but ra- 

 pidly in winter and spring, reaching lengths of about 10 cm. in the first 

 year, about 18 cm. in the following year and more than 20 cm. in the 

 third year. The annual yield amounts at a maximum to about 3 Kg. 

 wet weight per square meter. 



Okamura (8) found that small pieces of Gelidium plants regenerate 

 rhizoids and continue to grow on a new substratum. 



The researches on the relationship between Gelidium and other 

 algae and animals living in association on the Gelidium field may be 

 important, but the work on this subject is still incomplete. The young 

 plants are damaged by being covered by algae such as various species 



