PLATE 1 



EXPLANATION OF FIGURES 



1 to 5 Fwndulus heterocHlus 9 X Fundulus heteroclilus cf . 

 1 and 2 Anaphase of the third cleavage. The drawings do not show all of the 

 chromosomes that were present in the section. 



3 Polar view of an anaphase plate of the third cleavage. Forty-five chromo- 

 somes present. Magnification about 1800 diameters. 



4 An early anaphase of the third cleavage showing the shorter rods. 



5 An early anaphase of the third cleavage. Division is not complete in all 

 of the rods. 



264 



