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A. FRANKLIN SHULL 



means of weighing the evidence, the two phenomena might doubt- 

 fully be referred one to the other. 



Since oocytes of all stages of growth are included in table 4, 

 it is important, to know whether relative nuclear volume varies 

 with the size of the cell. To determine this point, all drawings of 

 oocytes were sorted into groups, all cells of one group being of 

 approximately the same size. The relative nuclear volumes were 

 then averaged for each size group separately, with the results 

 shown in table 5. 



There is a distinct decrease of relative nuclear volume during 

 the growth of the cell. The growth of the nucleus does not keep 



TABLE 4 



The relative nuclear volume of the oocytes of Hydatina senta for each of nineteen 



generations of the same line as is represented in tables 2 and 3 



pace with that of the cytoplasm. It is obvious that, if any 

 generations, or groups of generations, in the parthenogenetic line 

 which formed the basis of this study had furnished for measure- 

 ment an undue percentage of oocytes of any given stage of de- 

 velopment, the relative nuclear volume determined from the 

 measurements might have departed considerably from the true 

 mean. There was no reason why the data should have happened 

 to be 'loaded' in this manner, but to make sure that there was no 

 such source of error the measurements were collected into groups, 

 with respect to both cell size and the generation from which the 

 cells came. The results need not be given in detail; it seemed 



