gg0 THE REPRODUCTIVE ORGANS 



which surround, sometimes a small cavity, but more frequently a small stelli- 

 form mass of substance, from which delicate processes pass as septa between 

 the several lobules. The processes gradually change till they nearly fill the 

 cavity of the follicle, and even protrude from the orifice in the external cover- 

 ing of the ovary. Subsequently this orifice closes, but the fleshy growth within 

 still increases during the earlier period of pregnancy, the color of the substance 

 gradually changing to yellow, and its consistence becoming firmer. After 

 the orifice of the follicle has closed, the growth of the yellow substance con- 

 tinues during the first half of pregnancy, till the cavity is reduced to a com- 

 paratively small size or is obliterated; in the latter case, merely a white stelli- 

 form cicatrix remains in the center of the corpus luteum. 



The first changes of the internal coat of the Graafian follicle in the proc- 

 ess of formation of a corpus luteum seem to occur in every case in which an 

 ovum escapes. 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 impreg- 

 nation. 



The significance of the corpus luteum is found in the belief that it is the 

 portion of the ovary especially concerned in the production of an internal 

 secretion that affects the uterus, especially stimulating it at and before the 

 menstrual period. 



Menstrual Life. The occurrence of a menstrual discharge is one 

 of the most prominent indications of the commencement of puberty^ in the 

 female sex; though its absence even for several years is not necessarily at- 

 tended with arrest of the other characters of this period of life or incapability 

 of impregnation. The average time of its first appearance in females of this 

 country and others of about the same latitude is from fourteen to fifteen: 

 but it is much influenced by the kind of life to which girls are subjected, being 

 accelerated by habits of luxury and indolence, and retarded by contrary con- 

 ditions. Its appearance may be slightly earlier in persons dwelling in warm 

 climates than in those inhabiting colder latitudes. The menstrual functions 

 continue through the whole fruitful period of a woman's life, and usually 

 cease between the forty-fifth and fiftieth years, which time is known as the 

 climacteric. Menstruation does not usually occur in pregnant women. 



