THE CORPUS LUTEUM 727 



series of experiments, came to the conclusion that it is only so 

 long as there is a functional ovary present, that is one that is 

 capable of producing ripe ova, that it influences the general 

 metabolism of the body. 



To Prennant (17), in 1898, belongs the honour of being the 

 first to suggest that the corpus luteum was an actively secreting 

 gland of the variety we now call ductless glands, i.e. a gland in 

 which the secretion, instead of being conveyed to a definite place 

 by a duct, is transferred from the cells of the gland into the 

 blood stream. Three years later Regaud et Policard (18) 

 demonstrated that by means of a special method of staining, 

 specific droplets of secretion can be found in the lutein cells. 

 These droplets are coloured readily by Weigert's stain, and 

 although similar to are yet different from fat globules. Cohn (5), 

 again, working on the ovary of the rabbit, found that the 

 Plessen-Rabonowicz method of staining brought out in the 

 lutein cells vesicles surrounded by a kind of capsule and 

 containing a substance resembling fat but not identical with it. 

 Other authors have described an osmophile substance in these 

 cells, and, again, granules of a doubly refracting substance. 



As a result of chemical analysis various substances are stated 

 to be present, a substance sui generis, lutein, cholesterin, or 

 .again lipoids with or without phosphorus, and also ethers of 

 cholesterin. In his latest paper Van der Stricht gives a full 

 review of the chemical aspect of the problem and the reader is 

 referred thereto for further details. 



The evidence available is strongly in favour of regarding the 

 corpus luteum as a ductless gland that produces a specific 

 secretion which may be a lipoid or a mixture of lipoids. 



Thus we see that in the mammalian ovary at recurring periods 

 a highly specialised glandular structure producing a specific 

 secretion is developed which, after a period of activity very 

 short compared with the life of the animal, disappears only to 

 be replaced subsequently by another similar body. Further, 

 it is noteworthy that it is present at those times when either 

 the animal becomes pregnant or there is a possibility of preg- 

 nancy. In other words it appears immediately after ripe ova 

 have been discharged from the ovary. It is perhaps not unnatural 

 therefore that we should look for some connection between it 

 and the changes marking the beginning of pregnancy. The 

 extent and nature of these connections will now be considered. 

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