NUCLEOrLASMIC RELATIONS IN ARCELLA 



49 



TABLE 19 



Arcella polypora. Family ap. 5, line ape. 7. Table showing the mean diameter of 

 specimens with different nuclear numbers loithin a line derived from a uninucleate 

 piece of a sjyecimen with 4 nuclei and a diameter of 28 units. The unit of measure- 

 ment is 4-S M 



cleate specimens. All four of them immediately underwent 

 nuclear doubling, and they and their offspring then each pos- 

 sessed 4 nuclei. 



Line ape. 9 is interesting because the binucleate condition was 

 here maintained for a period of thirty-eight days (June 21st to 

 July 29th) , during which nine generations were obtained without 

 the intervention of a nuclear change. Seventeen specimens were 

 recorded during this period, the last of which possessed 4 nuclei 

 and all the others 2. The diameter of the sixteen binucleate 

 specimens ranged from 15 to 22 units with a mean of 18.80. 

 One empty shell was produced in this line. From these data it 

 appears that a binucleate line is not easily obtained and will not 

 persist for any great length of time. 



In table 20 is given the distribution of the diameters of the 

 specimens with 1 and 2 nuclei in the nine lines in this series. 

 The mean diameters of 19 units for the uninucleate class and of 



TABLE 20 



Arctila polypora. Family ap. 5. Table shoioing the distribution of the diameters 

 of the shells of specimens with 1 and 2 nuclei. The unit of measurement is 4.3 /x 



