176 Regulation of Size in Unicellular Organisms 



studied with respect to reproduction, and nuclear re- 

 lationships of which Geoffrey Smith ('03) proceeded 

 partially to analyze. In this species up to 650 nuclei 

 were present in a single vegetative individual. The 

 number of nuclei was found by Smith to be closely cor- 

 related with the dimensions of the individual. As far 



^500 

 ">400 



.£ 



cD 300 

 P- 



o 

 2200 



j£100 



o 



M^MM^MMNM .1 I » ^ _— 



So 



OS 



10 15 20 25 



Cube of mean diameter 



30 



Figure 58. Correlation between the number of nuclei and the cube of the 

 diameter (in arbitrary units) in Actinosphaerium eichhorni. Individuals 

 were grouped according to their diameters, and the modal numbers of nuclei 

 in each group are here plotted. (Data of G. Smith, '03). 



as the data indicate (figure 58) the number was prob- 

 ably proportional to the volume of the whole individ- 

 ual, and not to its diameter or its surface. 



The formation of cysts which was induced by lack 

 of food caused the death of most of the nuclei, leaving 

 a few, each of which then formed one cyst. The num- 

 ber of cysts formed also was found to be a function of 

 the size of the individuals in which they formed and 



