Il6 HARRIET RANDOLPH. 



Explanation of Plate I. 



All figures were drawn with Zeiss camera lucida, 2 mm. oil immersion objective, 

 12 ocular, enlarged 2 diameters with a drawing camera and reduced the same. 



Fig. I. Spermatogonium, resting stage, m (?), the "mitosoma" of Zweiger. 



Fig. 2. Spermatogonium, equatorial plate. /, the plasmosome. 



Fig. 3. First spermatocyte, synizesis stage, he, the heterochromosome. 



Fig. 4. First spermatocyte, synapsis stage. 



Fig. 5. First spermatocyte, spireme stage. 



Fig. 6. First spermatocyte, the heterochromosome pair partially separated from 

 the plasmosome. 



Fig. 7. First spermatocyte, the heterochromosome pair separated from the 

 plasmosome. 



Fig. 8. First spermatocyte, the chromosomes partially split. 



Fig. 9. First spermatocyte, prophase ; the forms of the chromosomes, all from 

 the same cyst. 



Fig. 10. First spermatocyte, prophase ; the six chromosomes in solid black are 

 at one pole and the five in outline at the opposite pole ; the one in heavy outline is at 

 the equator. 



Figs, ii and 12. First spermatocyte, prophase; the chromosomes on the way to 

 opposite poles under the influence of the centrosomes. 



Fig. 13. First spermatocyte, equatorial plate. 



Fig. 14. First spermatocyte, metaphase. 



Fig. 15. First spermatocyte, early anaphase. 



Figs. 16 and 17. Later anaphase stages. 



