28 



H. TAMIYA et at. 



vor. 12 (1953) 



remarkably. At about the looth hour, however, the Hght ceHs began to divide, wliich 

 was reflected in a sudden increase in cell number and dark cell ratio as well as the 

 decrease in average cell volume. 



HOURS 

 IN THE 

 LIGHT 



20 



43 



68 



99 



A=0.90 



A =0.83 





A = 0.59 



_1 EE 



n" 



A'O.se 



±M I L. 



A = 0.11 



40 



30 



20 



10 



% 

 30 



20 



10 



% 

 30 



20 



10 



% 

 30 



20 



W 



% 



- 40 



30 



- 20 



- 10 



12345618 9 10 



CELL DIAMETER IN /x 



PACKED CELL VOLUME PER LITER 



xlO^ 2 



7 

 



CELL NUMBER PER LITER 



-J 1 ' •■ : 1 1 I I 1 i_ 



AVERAGE CELL VOLUME 



20 40 60 80 WO 120 



HOURS IN THE LIGHT 



Fig. 4. Change of packed cell volume, cell nuniber, 

 average cell volume and dark cell ratio durins; 

 the transformation of dark cells into light cells. 

 ^Measurements were made with the same material 

 as that illustrated in Fig. 3. 



Fig. 3. Distribution polygons of cell diameter 

 showing the transformation of active dark cells 

 into light cells in the light. Shaded portions of 

 polygons indicate dark cells. The starting 

 material of dark-cell-rich culture was prepared 

 by growing the alga at 25", first under 10,000 lux 

 light for I weak, then under 400 lux for 3 days. 



The culture was placed in the dark for i day, before the cells were transferred mto fresh medium 

 for the main exj)criment. Main experiment was conducted at 9°-io~ C, with 2000 lux light, undi'r 



provision of COj-enriched air. 



I'rom other experiments, which we shall not reproduce here to save space, it was found that the 

 transformation of dark cells into light cells in the light, at least within first 20 hours of illumination, 

 was not affected markedly by the deprival of nitrogen or phosphorus or of whole nutrient salts from 

 the culture medium. But later the transformation was more or less markedly affected by nutrient 

 deficiency; in distilled water and in P-deficicnt medium it was halted completely at a certain stage, 

 and in N-deficient medium it was increasingly retarded with the progress of incubation. It was also 

 revealed that, during the course of transformation, the chlorophyll content of cells decreased, whereas 

 the total amount of chlorophyll in the culture* increased in normal medium, but not in P- or N-free 

 medium and in distilled water. 



* Calculated from the chlorophyll content of cells and the packed volume of cells contained in 

 the suspension. 



References p- 40. 



