790 EIGHTH PACIFIC SCIENCE CONGRESS 



The annual variation of the colour of the sea is similar to that of 

 the transparency, both with two maxima, one in summer and the other 

 in winter, and two minima, occurring in spring and autumn. As to 

 the seasonal variation of plankton volume, a very distinct maximum, 

 a phenomenon of the so-called burst growth, occurs in spring and a 

 less marked maximum in autumn, and a marked minimum appears in 

 winter, and also, in a less degiee, in early autumn. An experimental for- 

 mula D =- 21.8r-^-25, where D represents transparency expressed in 

 meters, and V the plankton volume in cc/m.% has been determined 

 (Fig. 5), although there are involved somewhat unsatisfactory conditions 

 such as the disregard of composition of plankton, the inequality between 

 the values of transparency and the depth of the net haul, etc. 



References 



(3) J. FuKUOKA and T. Yusa: The Variation of the Oceanic Condition in the 

 Sea Adjacent to Tohoku District. Oceanogr. Mog., Vol. 4, No. 2, 1952. 



(2) T. Nan'niti: On the Fluctuation of the Kurosiwo and the Oyasiwo. 



Papers in Meteor, and Geophys. (Meteorological Research Institute, 

 Tokyo), Vol. 2, No. 1, 1951. 



(3) J. FUKUOKA and T. TsuiKi: On the Variation of the Oceanographic Con- 



dition of the Sea near the Fixed Point "Extra."' Records of Oceanogr. 

 Works in Japan. (Japanese National Commission for Unesco) Vol. 1, 

 No. 1 (New Series), 1953. 



(4) M. Koizumi; On the Annual Variation in Oceanographical Elements at a 



Fixed Point (39°N, 153°E) in the Pacific Ocean. Records of Oceanogr. 

 Works in Japan. (Japanese National Commission for Unesco) Vol. 1, 

 No. 1 (New Series), 1953. 



