EXPLANATION OF FIGURES 



Figures 8 to 12 were drawn in outline with a projection lantern and the details 

 filled in from the specimens. The other figures were all drawn with a camera 

 lucida, at table level. Text figures 1 to 6 were made with the aid of a Zeiss 

 apochromatic objective, 2 mm., 1.4 N. A., and compensating ocular X 8, at a 

 magnification of 1875 diameters; the cuts, reduced to one third, are X 625. Figure 

 7 was drawn at a magnification of 133 and reduced to one third (X 44). The 

 other figures, with the exception of 51, were made with a Zeiss apochromatic 

 objective, 2 mm., 1.4 N. A., and compensating ocular X 12, at a magnification of 

 2667 diameters; reduced one fourth off, they are X 2000 in the plates. Figure 51 

 was drawn with compensating ocular X 6, and is half this magnification. 



I wish to express my appreciation of the careful and painstaking work of Mr. 

 R. S. Outsell who made all my drawings for me. 



ABBREVIATIONS 



Czi //., Weigert's copper hematoxylin P.A.F., Picro-aceto-formol (Bouin's) 



Fl., Flemming's fluid p.p., Post-partum 



Herm., Hermann's fluid Tri., Flemming's triple stain (safran- 

 I.H., Heidenhain's iron hematoxylin in, gentian violet, and orange G.) 



PLATE 1 



EXPLANATION OF FIGURES 



8 Transection of ovary of embryo 11 mm. long. The oviduct (Miillerian 

 duct) is at the left in a fold which later forms the perioan capsule. X 67. 



9 Transection of ovary of embryo 17 mm. X 67. 



10 Transection of ovary of mouse between 9 and 19 hours after birth. The 

 capsule completely surrounds the ovary. X 67. 



11 Transection of ovaiy of mouse 10 days after birth. The capsule was 

 left out of this drawing. X 67. 



12 Transection of ovary of mouse 15 days post partum. The center is 

 filled with large follicles containing primitive oocytes. X 33. 



13 Transection of ovary of mouse 39 days old— practically sexually mature. 

 The definitive cortex filled with definitive oocytes in their follicles is shown, and 

 the medulla with its blood vessels, stroma, etc. X 33. 



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