Size of Nucleus 



183 



the ratio of body to nucleus is almost constant over a 

 large range of modifications of body size caused by 

 temperature. 



Hunger. Starvation has been found by many to be 

 a potent factor in nuclear size. Most of the studies 

 of this factor have been of organisms cultivated under 



140 

 120 



100 



§ 80 

 o 





60 

 40 

 20 



B 



ody-ruclear ratio 



Vnhi-Tift of -nucleus ^» 



-<?» 



£gQ^ gg 



PdKjrnecu m 



o\a 



• — a 



10 12 14 16 18 20 22 



Temperature -°C. 



24 Z6 



Figure 61. Effect of temperature upon the ratio of body volume to nuclear 

 volume, and upon the volume of the nucleus, in three species of ciliates. 

 Only average results are shown, including those for Paramecium which are 

 shown in detail in figure 60. (Data of Popoff, '08, and of Rautmann, '09). 



rather unknown conditions; lack of food was not ab- 

 solute but the individuals observed were simply in old 

 cultures which did not allow multiplication to pro- 

 ceed. 



Interest in this factor was aroused by the observa- 

 tion of Hertwig ('98, '00, '04), upon the heliozoan Ac- 

 tinosphaerium, that a few of the many nuclei were 

 greatly enlarged in old cultures. While normal in- 



