1 66 A. RICHARDS. 



EXPLANATION OF PLATE II. 



FIGS, i and 2. Parenchyma cells for comparison with the cells of the primary 

 anlage; from young proglottids. Fig. 2 illustrates the arrangement of the cells in 

 pairs common in all undifferentiated tissue of the cestode. Cytoplasmic boundaries 

 are difficult to make out in such cells as these in all but the best fixed specimens. 



FIGS. 3-5. From primary anlage in same section as Fig. 2. Fig. 3 is from the 

 inner growing end of the anlage, to be the ovary; Fig. 4 is from the middle region, 

 to develop into the vitellarium, etc.; Fig. 5 is from the outer growing tip, to form the 

 vagina. Hermann, iron haematoxylin. 



FIGS. 6 and 7. From the primary anlage of the same section from which Fig. I 

 was taken; Fig. 6 from the middle, Fig. 7 from the outer end. Zenker, Ehrlich- 

 Biondi. 



FIG. 8. A case of mitosis in the primary anlage. King, iron haematoxylin. 



FIG. 9. Mitosis in a pre-oogonium. Zenker, safranin and gentian violet. 



FIG. 10. Polar view of a mitosis from the same anlage as Fig. 9. 



FIG. ii. Cell from near the growing tip of the ovary anlage; a pre-oogonium. 

 Zenker, Ehrlich-Biondi. 



FIG. 12. Group of pre-oogonia just before the formation of the follicular mem- 

 brane. Cytoplasmic boundaries are not well preserved in all cases. The over- 

 lapping of such nuclei as are shown here gives a misleading suggestion of amitosis. 

 King, iron haematoxylin. 



FIG. 13. A stage in the mitosis of a late pre-oogonium before the condensation 

 of the chromosomes. Hermann, iron haematoxylin. 



FIG. 14. The most distinct case of mitosis found throughout the oogenesis; 

 spindle fiber bundles are very strong. A late pre-oogonium. King, Ehrlich-Biondi. 



FIG. 15. Pre-oogonium, slightly later than Fig. 12. King, iron haematoxylin. 



FIG. 16. A young oogonium in mitosis; polar view. Zenker, iron haematoxylin. 



