49G J. BRONTE GATENBY 



Fig. G. — Part of the testis of Ornithorhynchus. For description see 

 p. 492 of text. 



Plate 14. 



Figs. 7 and 8. — Two of the youngest oocytes or Ornithorhynchus, 

 sliowing s])hcrc and mitochondria. 



Fig. 9. — Edge of young egg showing relationship of follicle to cell 

 (oocyte) membrane. 



Fig. 10. — Egg at time of formation of prc-zona (pz) follicle, one-layered. 



Fig. 11. — Later stage, zona formed, follicle two-layered. 



Fig. 12. — Follicle and part of egg at stage little later than in fig. 10, 

 showing pre-zona substance apparently within follicle wall. Two layers 

 of nuclei just forming in follicle. 



Fig. 13. — Detail of later egg, showing membranes. Mitochondria at m. 



Fig. 14. — Cortex of later egg showing arrangement of layer beneath the 

 zona. 



