THE REPRODUCTIVE SYSTEM. 



tioned; or, very possibly, coagulation occurs, but the process is more or 

 less spoiled, and what clot is formed is broken down again, so as to imi- 

 tate liquid blood. 



Menstruation, therefore, is not the result of congestion, or of a species 

 of erection, but of a destructive process by which the decidua or nidus 

 prepared for an impregnated ovum is carried away. It is not a sign of 

 the capability of being impregnated as much as of disappointed impreg- 

 nation. 



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 

 attended with arrest of the other characters of this period of life, or with 

 inapt-ness for sexual union, or incapability of impregnation. The ave- 

 rage 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 in- 

 fluenced by the kind of life to which girls are subjected, being accele- 

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

 ditions. On the whole, its appearance is earlier in persons dwelling in 

 warm climes than in those inhabiting colder latitudes; though the exten- 

 sive investigations of Eobertson show that the influence of temperature 

 on the development of puberty has been exaggerated. Much of the 

 influence attributed to climate appears due to the custom prevalent in 

 many hot countries, as in Hindostan, of giving girls in marriage at a, 

 very early age, and inducing sexual excitement previous to the proper 

 menstrual time. The menstrual functions continue through the whole 

 fruitful period of a woman's life, and usually cease between the forty- 

 fifth and fiftieth years. 



The several menstrual periods usually occur at intervals of a lunar 

 month, the duration of each being from three to six days. In some 

 women the intervals are as short as three weeks or even less; while in 

 others they are longer than a month. The periodical return is usually 

 attended by pain in the loins, a sense of fatigue in the lower limbs, and 

 other symptoms, which are different in different individuals. Menstrua- 

 tion does not usually occur in pregnant women, or in those who are 

 suckling; but instances of its occurrence in both these conditions are by 

 no means rare. 



Corpus Luteum. Immediately before, as well as subsequent to, 

 the rupture of a Graafian vesicle, and the escape of its ovum, certain 

 changes ensue in the interior of the vesicle, which result in the produc- 

 tion of a yellowish mass, termed a Corpus luteum. 



When fully formed the corpus luteum of mammiferous animals is a 

 roundish solid body, of a yellowish or orange color, and composed of a 

 number of lobules, which surround, sometimes a small cavity, but more 

 frequently a small stelliform mass of white substance, from which deli- 



