Plate II. 

 Ovaries of immature rats ( X 22) 



Fig. 5. Normal animal. 



Fig. 6. Fifteen days after 

 physectomy. 



hypo- 



Fig. 7. Fifteen days after hypo- 

 physectomy and oestrogen treatment. 



Fig. 8. Twenty-two days after hypo- 



physectomy ; oestrogen treatment 



started I? days after operation. 



