Spirogyra Cells 



201 



latter in fact stopped growing. The cells with double 

 quantities of nuclear material might exhibit two dis- 

 crete nuclei, or one nucleus of a double size, or one 

 nucleus made up of two connected lobes. In all cells 

 the nuclei were suspended in the cell sap and were usu- 

 ally discoidal in shape, so that their dimensions could 

 be measured and their volumes calculated. 



The homogeneous character of the nuclear sizes is 

 shown in frequency tables contained in Gerassimow's 

 ('01) publication. Gerassimow based his comparisons 

 upon mean volumes; double nuclei had on the average 



Table 14. 



Mean Dimensions of Nuclei in Normal and in Double-Nucleated 

 Cells of Spirogyra Bellis. (Data of Gerassimow, '01 and '02.) 



1.94 times the volume of the normal nuclei. In the case 

 of cells containing two discrete nuclei the volume of 

 each nucleus was exactly the same as of a normal nu- 

 cleus. The nuclei, therefore, exhibited their inherited 

 quantitative characters with respect to their own sizes 

 (table 14). 



Gerassimow ('02) also measured the sizes of the cells 

 themselves, which contained single and double quanti- 

 ties of nuclear material. For this purpose he meas- 

 ured the lengths and diameters of about 26,600 cells. 

 The distribution of the various dimensions is shown 

 in the series of frequency curves (figure 65) construc- 

 ted from his data. It appears that the percentage vari- 

 ability in volume was very much larger in the bivalent 

 cells; evidently the length and the surface were more 



