548 E. V. COWDEY 



when the egg reaches the uterus. He is of the opinion that it exercises a 

 directive influence upon uterine changes occurring at the same time. 



The lipoid secretion is preceded by the accumulation of fat in the lutein 

 cells. At first this fat blackens with osmic acid, but later on, according to 

 Van der Stricht, it becomes changed into droplets of lipoid, which are 

 excreted into the intercellular spaces and lymphatics. These spaces be- 



Fig. 6. Cells of human corpus luteum illustrating close relationship to the capil- 

 laries (magnification 720). 



come so dilated with material that they assume the appearance of veritable 

 ducts, and the living cells simulate true glandular epithelium. That the 

 lutein cells are not definitely polarized, however, is shown by Van der 

 Stricht's observation that the centrosomes are distributed without order in 

 the cytoplasm. Since this lipoid secretion begins shortly after the rupture 

 of the Graafian follicle, and increases gradually until about the end of preg- 

 nancy, he concludes that it functions chiefly in bringing about the arrest 

 and fixation of the egg and the development of the placenta. He believes 



