PLATE 3 



EXPLANATION OF FIGURES 



N. glauca, second division. X 2000 



35 Telophase of the first division, prophase of the second, showing both huge 

 chromosomes. 



36 Metaphase, side view, showing large compound chromosome and XY. 



37 A, B, C Serial sections of entire spindle in side view, showing complete 

 set of 12 chromosomes. 



38 A, B, C Same, only X and Y are on different fibers. 



39 and 40 Polar view, showing 12 chromosomes. Both X and Y appear in the 

 center. 



41 Side view of a metaphase spindle, showing two large and two small chro- 

 mosomes. 



42 XY chromosomes from one individual. 



43 XY chromosomes from another individual, showing greater inequality of 

 the two chromosomes. 



44 Early anaphase showing large chromosomes and XY. 



45 Late anaphase, showing two large chromosomes near upper pole and larg- 

 est one near lower pole. 



46 Late anaphase, showing largest chromosome near pole. 



47 A, B Sister anaphase groups from same spindle, central chromosomes (X 

 and Y) considerably unequal. 



48 A, B Same, X and Y more nearly equal. 



49 Spermatogonial group, showing large chromosomes and small ones. 



50 Oogonial group showing 24 chromosomes. 



152 



