NUCLEOPLASMIC RELATIONS IN ARCELLA 59 



h. Simimary of results of observations and experiments on Arcella 



polypora 



1. The nuclear number of fifty-four wild specimens ranged 

 from 3 to 10 and the diameters of the same from 25 to 33 units 

 of 4.3 iJL each. The coefficient of correlation between the nuclear 

 number and the diameter of these specimens was .156 ±.089. 



2. Variations in diameter within families reared from wild 

 specimens were much greater than those exhibited by Arcella 

 dentata. This is due to changes in nuclear number within the 



Fig. 39 Arcella polj'pora. Outline of a specimen from Bloomington, New 

 York, with comparatively large mouth. X 207. 



families, such changes being accompanied by corresponding 

 changes in diameter. 



3. Different families differ constitutionally in diameter, and 

 the data derived from the study of twenty-six families indicate 

 that an indefinite number of families of different mean diameters- 

 exist in nature. 



4. The correlation between parents and offspring with respect 

 to diameter in a population consisting of twenty-five small fami- 

 lies is very close (.740 ± .018). 



5. Breeding experiments with a large family (ap. 5) gave the 

 following results : 



a. Correlation between the diameters of parents and offspring 

 within the family was marked (.442 ± .041). 



