GENERATION AND DEVELOPMENT. 



245 



braniform sac, lining the corpus luteum. At other times the serum is re- 

 moved, and the fibrin constitutes a solid stelliform mass. 



The yellow substance of which the corpus luteum consists, both in 

 the human subject and in the domestic animals, is a growth from the 

 inner surface of the Graafian vesicle, the result of an increased develop- 

 ment of the cells forming the membrana granulosa, which naturally lines 

 the internal tunic of the vesicle. 



The first changes of the internal coat of the Graafian vesicle in the 

 process of formation of a corpus luteum, seem to occur in every case in 

 which an ovum escapes; as well in the human subject as in the domestic 

 quadrupeds. If the ovum is impregnated, the growth of the yellow sub- 

 stance continues during nearly the whole period of gestation, and forms 

 the large corpus luteum commonly described as a characteristic mark of 

 impregnation. If the ovum is not impregnated, the growth of yellow 

 substance on the internal surface of the vesicle proceeds, in the human 

 ovary, no further than the formation of a thin layer, which shortly disap- 

 pears; but in the domestic animals it continues for some time after the 

 ovum has perished, and forms a corpus luteum of considerable size. The 

 fact that a structure, in its essential characters similar to, though smaller 

 than, a corpus luteum observed during pregnancy, is formed in the 

 human subject, independent of impregnation or of sexual union, coupled 

 with the varieties in size of corpora lutea formed during pregnancy, neces- 

 sarily renders unsafe all evidence of previous impregnation founded on 

 the existence of a corpus luteum in the ovary. 



The following table by Dalton, expresses well the differences between 

 the corpus luteum of the pregnant and unimpregnated condition re- 

 spectively. 



CORPEUS LUTEUM OP 

 MENSTRUATION 



CORPUS LUTEUM OF PREG- 

 NANCY. 



At the end of 



three weeks. 

 One month . 



Tivo months 

 Six months . 

 Nine months 



Three-quarters of an inch in diameter ; central clot red- 

 dish ; convoluted wall pale. 



Smaller ; convoluted 

 wall bright yellow ; 

 clot still reddish. 



Reduced to the con- 

 dition of an insig- 

 nificant cicatrix. 



Absent. 



Absent. 



Larger ; convoluted wall bright 

 yellow ; clot still reddish. 



Seven-eighths of an inch in diame- 

 ter; convoluted wall bright yel- 

 low ; clot perfectly decolorized. 



Still as large as at end of second 

 month ; clot fibrinous ; convo- 

 luted wall paler. 



One-half an inch in diameter ; 

 central clot converted into a 

 radiating cicatrix ; the external 

 wall tolerably thick and convo- 

 luted, but without any bright 

 yellow color. 



