336 



THE AMERICAN NATURALIST [Vol. LV 



diameters, is given in square millimeters. The coefficient 

 of correlation is remarkably high, namely, .755 ± .016 ; 

 this proves that an increase in size is accompanied by a 

 corresponding increase in nuclear number. The rest of 

 the specimens that were measured, 114 in number, were 

 drawn at a magnification of 1400 diameters. The coeffi- 

 cient of correlation of this lot was found to be .875 ± .015. 



TABLE I 



Correlation Table for Number of Nuclei and Area of 341 Specimens 

 Tlie area is given in sq. nun. and obtainod from camora-lucida drawings 

 made at a magnification of 650 diameters. Coefiacient of correlation 

 .755 ± .016. 



Metcalfe has pointed out that in multinucleate Opalinas 

 the nuclei within a single specimen may be in different 

 stages of division at one time. This we have found to 

 be true also o\' tlic niiclci during the growth stages in the 

 t.Hlfiolc ;i conditioii tli;il li;is enabled US to analyze with 



M,.t,-,iir. .\r. .\r., lltn:., ••O/,,,//,,,,.-- An-n. f. Protist., 13: 195-375. Es- 



