NUCLEOPLASMIC RELATIONS IN ARCELLA 



53 



according to nuclear number. The coefficient of correlation be- 

 tween nuclear number and diameter within family ap. 34 is 

 very similar to that within family ap. 5 (table 15), but in the 

 former a particular number of nuclei is on the average associated 

 with a diameter about 4 units smaller than within family ap. 5. 

 Furthermore, the variation in the number of nuclei is different, 

 since in family ap. 5 specimens with from 3 to 7 nuclei were ob- 

 tained without recourse to cutting experiments, whereas in family 

 ap. 34 the range was from 5 to 10. Figure 37 shows by means of 



TABLE 21 



Arcella polypora. Family ap. 34- Correlation table for number cf nuclei and 

 diameter of shell in 302 specimens. The unit of measurement is 4.3 ii. Coeffi- 

 cient of correlation, 0.699 ± 0.020 



curves the similarity in diameter of the group in family ap. 5 

 with 4 nuclei and of the group in family ap. 34 with 7 nuclei. 

 Diverse lines with 7 nuclei within family ap. 34. During the 

 course of the work with family ap. 34 it was noticed that several 

 of the branches that contained mostly specimens with 7 nuclei, 

 differed considerably in size. Members of these branches were 

 kept for eight generations and during the entire period of twenty 

 days covered by these generations the difference in diameter per- 

 sisted (fig. 38). The distribution according to diameters of these 

 two lines was as follows : 



