2O8 S. W. GE1SER. 



EXPLANATION OF THE FIGURES. 



(All figures were drawn at table level with the aid of a camera-lucida, using 

 a 1.8 Bausch & Lomb Fluorite oil immersion with a Zeiss No. 12 compensating 

 ocular at a tube-length of i6omm. The drawings thus obtained were enlarged 

 1.75 diameters with a pantagraph. These final drawings were reproduced 

 without reduction. 



PLATE I. 



FIGS. 1-2. Dividing spermatogonia from the peripheral portion of the 

 testis. 



FIGS. 3-5. Spermatogonia in multiplication-divisions in the cyst. 



FIGS. 6-7. Stages later than the preceding, showing reconstitution of the 

 nucleus after spermatogonial divisions. 



FIGS. 8-10. Final spermatogonia. 



FIGS. 11-16. Leptotene stages. 



FIG. 18. Pachytene. 



FIG. 19. Cell in the pachytene stage, cut transversely to the chromatin 

 threads. 



