36 



ROBERT W. HEGNER 



TABLE 9 

 Arcella polypora. Correlation table for number of nuclei and diameter of shell in 

 fifty-four specimens collected at Baltimore. The unit of measurement is 4.3 fi. 

 Coefficient of correlation 0.156 =t 0.089 



c. Variations in diameter within families 



Thirty-three specimens were isolated on culture slides and 

 from these twenty-five small families and one large family 

 were reared. The most striking difference between these 

 families and those reared from specimens of A. dentata was 

 the great variations in size that often occurred between parent 

 and offspring. The following are examples of some of these 

 differences : 



Part of the pedigree of family 22 (fig. 31) shows several of these 

 large variations in diameter. 



