The sex of the Japanese eel could be controlled by the oral administration of DES-Na (sodium diethylstilbestrol) which also promoted growth. Elvers were reared from glass eels for more than 500 days with a commercial feed which contained DES-Na (0 , 0.5, 0.75, 1.0 ppm).All the eels were dissected at the end of the experiment to check the sex by both external appearance and histological examinations of gonads.The sex groups were divided into male, male?, female, female? and unknown by their external appearance, and into male, female, hermaphrodite, and non-sex by histological examination.The largest discrepancy (27.5%) in the two examinations was found in the male: the histological examination was found to be essential.The female ratio increased along with an increase in DES-Na.It was 7.7% in the control and 23 .2-35.4% in DES-Na groups. The male ratio was 64.1% in the control and 32.0-40.4% in DES-Na groups.The hermaphrodite ratio was 1.1-4.6%, and the non-sexual ratio was 23.8-38.0%.Females were the largest of all sex groups. The growth promoting effect was found to vary with the growth stage.

No abstract

I odometric colorimetry is applied for measuring COD(Mn), using hydrogen peroxide as the mediator. It saves time, space, and chemicals without degradation of accuracy. The method can be applied to any digestion method which uses permanganate. The remaining permanganate is reduced by hydrogen peroxide at pH 1-2, where the peroxide is stable. If the silver ion for masking halides remains in the digested mixture, it is made to settle on the reduction by an excess of sodium chloride. The supernatant of digested mixture is transferred to 0.3M KI in the acetate buffer (pH 5-6) which contains molybdate (catalyst). As the peroxide oxidizes iodide within 2 min, the formed triiodide is colorimetrically measured at 353nm within 2h of reaction. Blank increase by air oxidation can be ignored during this time. The method of controlling the pH of the reaction mixture is also described.

Summary.To understand the functions of the longitudinal and transverse flagella of dinoflagellates, the flagellar waveform and frequency of each flagellum were observed by high-speed video-recording. The longitudinal flagellum emerged from the anterior end of the cell and beat with a planar undulating wave whose plane was perpendicular to the valval sutural plane. The transverse flagellum curved around the anterior end of the cell and beat with a helical wave, with different alternating half pitches. The half pitch corresponding to the parts farther from the cellular antero-posterior axis was shorter than that of the parts closer to the axis. This pattern is described by the ratio of the outer-parts half pitch to the pitch of the whole period of the helix and seems to be characteristic of the dinoflagellates' transverse flagellum.