THE REPRODUCTIVE ORGANS 83 



are, however, in favour of the view that the luteal cells are 

 derived from the follicular cells. 



The glandular nature of the organ is admirably shown in 

 the corpus luteum oiDasyuru3 (see Figs. 13 and 13a,). 



The yellow pigment of the corpus luteum belongs to the 

 group of lipochromes. These are found in several organs and 

 tissues and are related to similar vegetable pigments. The 

 lutein from egg-yolk has a molecular weight of 624 and the 

 formu'a given is C 40 H 56 C) 2 . It is isomeric with xanthophyll, 



FIG. 13a. Portion of corpus luteum of Dasyurus under a high power, showing 

 the glandular nature of the constituent cells. (Drawn by Mrs. F. D. 

 Thompson from material supplied by Prof. Charles O'Donoghue.) 



obtained as a by-product in the preparation of chlorophyl. 

 The precise chemical nature of lutein has not yet been made 

 out, but it has been suggested that it is an oxidation product 

 of carotin (obtained from carrots), or again, that it is an oxida- 

 tion product of the esters of cholesterol with unsaturated 

 acids. 



Different " active principles " have been isolated from corpora 

 lutea by means of different solvents. Thus some of these are 

 extracted by ether, others by acetone. If these are to be 



