THOMAS H. MONTGOMERY. 



EXPLANATION OF PLATES I-V 



All figures have been drawn by the author with the camera lucida at the level 

 of the base of the microscope, and reduced one third in size in reproduction. Fig. 50 

 was drawn with Zeiss obj. C, ocular 12, all the others with the apochromatic im- 

 mersion objective 1.5 mm., ocular 12. 



The following abbreviations have been employed: 



Id., idiozome. 



R., rod. 



r. i, primary rodlet. 



r. 2, secondary rodlets. 



S.C., Sertoli cells. 



Sp.G., ultimate spermatogonia. 



PLATE I. 



FIGS. 1-3. Entire antepenultimate spermatogonia. 

 FIGS. 4-8. Rods of antepenultimate spermatogonia. 

 FIG. 9. A binucleate penultimate spermatogonium. 

 FIGS. 10, ii. Penultimate spermatogonia. 



