BY F. P. SANDES. 3G9 



Ovary, Stage C. 



Five days post coitiim, ova in one- and two-cell stages. 



Ovary, Stage D. 



Ova in the sixteen- and tliirty-tvvo-cell stages, with unclosed 

 hlastodernuc vesicles in some cases. 



Ovar}^, Stage E. 



Blastodermic vesicles, average diam. 1 mm. 



Ovary, Stage F. 



Blastodermic vesicles, average diam. 2-5 to 3 mm. 



Ovary, Stage F^. 



Blastodermic vesicles, max. diam. 3-5 mm. 



Ovary, Stage G. 



Blastodermic vesicles, average diam. 3 '5 to 4 mm. 



Ovary, Stage H. 



Blastodermic vesicles, average diam. 6-5 to 7 mm. Showing 

 primitive streak and head process. Very large corpora lutea 

 projecting on the surface of the ovary. This is about the stage 

 of full development of the corpus luteum. 



Ovary, Stage K. 



Embryo 5-75 mm. long; late uterine stage, about the seventh 

 day. 



Ovary, Stage L. 



New born young, three hours old, in pouch. 



Ovary, Stage M. 



Very small ovary, young animals 105 mm. long, head length 

 45 mm. 



Definition of Terms. 



It will tend to avoid confusion if, before proceeding further, 

 there be obtained a clear conception of what is meant by certain 

 terms as used in this paper. All authors are not agreed as to 

 the use of the terms "corpus luteum," "corpus luteum verum," 

 " corpus luteum spurium vel falsum," and " corpus luteum 

 23 



