THE CORPUS LUTEUM OF PREGNANCY IN SWINE. 70 



which are rather diagrammatic, show the granules clustered closely about the nucleus, bul 

 I generally find them more or less diffusely scattered through the endoplasm. When the 

 endoplasm reaches to the periphery, as it does in the later stages, then consequently the 

 granules are seen throughout the cell. As to their nature and function we can only guess. 

 As they are not dissolved from fixed tissues by ether, alcohol, or water, and because they are 

 preserved by mercury salts, Cesa-Bianchi thinks they are of albuminous nature. I see no 

 reason to think otherwise, although one hesitates to speculate on the chemical nature 

 during life of minute objects which one does not see until they have been through •">(• to 70 

 changes of reagents. It has impressed me strongly that the staining reactions of the 

 endoplasmic granules are the same as those of the peculiar rings found in the exoplasm, 

 Now, in the life-history of the lutein cell, as we shall see later, the exoplasm recedes as tin' 

 endoplasm becomes wider, and the granules seem to increase in proportion to the amount 

 of the endoplasm. It occurs to me that possibly the two structures are but stages in the 

 same process. Cesa-Bianchi presumes the granules to be connected with the supposed 

 phenomena of internal secretion of the corpus luteum, and that his findings support the 

 theory of an internal secretion; a view based of course on analogy, but one which must be 

 kept in mind. 



In the corpus luteum of the sow I do not observe the yellow granules of pigment which 

 are said to be plainly visible in the corpus of the cow, and concerning which the remarkable 

 discovery has recently been made by Escher (1913) that in chemical composition the sub- 

 stance is identical in all reactions with the lipochrome body carotin, found in carrots and 

 green leaves. 



LIFE HISTORY OF THE LUTEIN CELL OF PREGNANCY. 



In the earliest corpus luteum of known age of pregnancy in my series of sections, the 

 lutein cells are fully formed and contain the peripheral ring-apparatus in a high state of 

 development. In discussing them at an earlier stage we tread upon debatable ground. In 

 a specimen to be described at length (p. 88, figs. 21, 22, 23), as an illustration of the 

 interesting anomaly known as partial accessory lutein-cell formation, the cells of the granu- 

 losa of the follicle in question, at the point where the supposed lutein-cell formation is taking 

 place, are swollen, possess vesicular nuclei, and contain in their cytoplasm very definite 

 canals having within them a few minute hyaline rings. The resemblance to the fully 

 formed lutein cell is striking. 



In corpora lutea of pregnancy of 20 to 25 mm., all the lutein cells are of about the same 

 size, are rounded in outline, and possess round vesicular nuclei relatively rich in chromatin. 

 The endoplasmic zone is almost nil, being crowded out by the great development of the 

 exoplasmic formations. The latter are composed of the ring-like structures previously 

 described, in a high stage of perfection. At this time the cells contain considerable quan- 

 tities of osmic-blackening substance, which almost fills some of the cells with good-sized 

 globules of varying magnitude, besides occurring, as shown by Cohn, in tiny droplets at the 

 centers of the spherical structures of the peripheral vacuolar apparatus (fig. 6, a). 



As the cells grow older the following changes take place, as shown in figures 4 to 15: 



(1) The nuclei become paler by reason of the lessening of the chromatin. 



(2) The ring-like formations give place to less elaborate forms; that is, to simple 

 clefts and V-shaped spaces in the cytoplasm, arranged concentrically to the nucleus. In 

 corpora lutea of old pregnancies (150 to 290 mm.) no sign of the once elaborate structure 

 is to be found in most cells. 



