308 J. E. WODSEDALEK. 



Zeleny, C. and Senay, C. T. 



'15 Variation in Head Length of Spermatozoa in Seven Additional Species of 

 Insects. Jour. Exp. Zool., Vol. 19, No. 4. 



EXPLANATION OF PLATES. 

 PLATE I. 



(All of the drawings were made with the aid of a camera lucida, X 2,400, except 

 Figs. 39 and 40 which are X 2,200.) 



FIG. i. Polar view of the metaphase of division in a spermatogonial cell show- 

 ing thirty-six ordinary chromosomes and the single heart-shaped sex-chromosome. 



FIG. 2. Side view of the metaphase of division in a spermatogonial cell showing 

 the thirty-six ordinary chromosomes, and the sex-chromosome at the left. 



FIGS. 3 AND 4. Late anaphases of division of spermatogonial cells showing the 

 division of all of the chromosomes, including the large sex-chromosome. 



FIGS. 5-9. Late prophase stages of the last spermatogonial cells. 



