198 



Regulation of Size in Unicellular Organisms 



('74) at intervals of a few minutes, and his data led him 

 to the surprising result that increase of length occurred 



16 



1.4 



CD 



E 



o f.2 



> 



CD 

 > 



3 



QJ 



t- 



CD 



E 



x: 



1.0 



Q8 



0.6 



o 



0.2 











4 6 8 



Time in days 



10 



12 



Figure 64. Growth in volume of normal and of double-nucleated cells of 

 Spirogyra bellis. Each point represents the average of 20 to 80 cells, most 

 of which were measured on two days besides the initial day. The normal 

 cells were all members of the same filaments with double-nucleated cells. 

 Volume was calculated as / X b 2 . (Data of Gerassimow, '01). 



in jumps. These jumps were at very irregular inter- 

 vals; as is brought out by the graphs of the data which 



