NUCLEOPLASMIC KELATIONS IN ARCELLA 



57 



TABLE 25 



Arcella polypora. Correlation table for diameter of mouth and diameter of shell 

 in eighty large wild specimens collected at Cold Spring Harbor, Long Island. 

 The unit of measurements is 4-3 n. Coefficient of correlation, 0.719 ± 0.036 



A. discoides. They are included here, however, because of the 

 probabiUty that they were multinucleate. The diameter of the 

 shell ranged from 215 // to 327 ix, and that of the mouth opening 

 from 99 M to 159 /x (fig. 39). The largest specimens of Arcella 

 that have hitherto been recorded were 300 ^ or less in diameter ; 

 these, therefore, are the largest that have ever been reported. 



The differences between the percentages of the diameter occu- 

 pied by the mouth in the different groups of specimens included 

 in table 22 are of particular interest. If these groups all belong 

 to the species polypora, then it seems evident that within the 

 species there are lines that differ in the relative diameter of shell 

 and mouth. Families ap. 5, ap. 34, and ap. 69 all fall in one 

 group, with a mean percentage of about 41 ; the large specimens 

 from Cold Spring Harbor in another, with a mean percentage of 

 about 54, and the large specimens from Bloomington, New York, 

 in a third, with a mean percentage of about 48. It is possible 

 that the diameter of the shell and the diameter of the mouth are 



