44 



H. L. WIEMAN. 



EXPLANATION OF PLATES. 



The figures are camera drawings made at table level with Zeiss apochromatic 

 objective, 1.5 mm. and compensating ocular, 12. There has been some reduction in 

 reproduction. • 



Plate I. 



Fig. I. Primary spermatocyte at the end of the growth period. Male pupa. 



Figs. 2, 3 and 4. Primary spermatocytes undergoing changes in outline pre- 

 liminary to the formation of the polar body. 



Figs. 5 and 6. Primary spermatocytes having chromosomes in the form of 

 loops or split rods. 



Figs. 7 and 8. Stages in the cutting off of the polar body. Fig. 8 contains a 

 second polar body belonging to a cell in a neighboring section. 



Fig. 9. Prophase of the second spermatocyte division showing 12 chromosomes. 



Fig. 10. Side view of the second spermatocyte spindle at metaphase. 



