22 



Regulation of Size in Unicellular Organisms 



killed immediately after fission; and three dimensions 

 were always measured. These individuals all showed 

 greater growth in breadth than in length, in this re- 

 spect being more extreme than those measured by 

 Estabrook. 



200 



Sl80 



CD 



£ l60 



'S 140 



o 

 CO 120 



1 °°0 2 4 6 8 



Time after fission in hours 



Figure 8. Growth in length and in volume in Paramecium caudatum at 

 25 °C. Each point represents a single individual which was fixed, and 

 measured in length, in breadth, and in thickness. Relative volumes were 

 calculated as / X b X *• (Data of Popoff, '09). 



Upon Paramecium aurelia, Erdmann ('20) found 

 much the same progression in body length (figure 9) 

 as did Jennings. Judging by the large number of in- 

 dividuals measured, these results should be significant. 

 But body breadth was not studied. 



