PUBERTY AND MENSTRUATION. 781 



cease at a correspondingly early period ; but this is by no means constant. 

 There are, also, many exceptions to the ordinary limits to the period of fe- 

 cundity. 



Although there is a periodical condition of heat in the lower animals, 

 connected with ovulation, a sanguineous discharge from the genital organs 

 is not often observed. It is only in monkeys that there is a counterpart of 

 what occurs in the human female ; and observations upon these animals have 

 shown that they are subject to a monthly discharge of blood, at this time 

 giving evidence of unusual salacity. 



In the human female, near the time of puberty, there is sometimes a peri- 

 odical, sero-mucous discharge from the genital organs, preceding, for a few 

 months, the regular establishment of the menstrual flow. Sometimes, also, 

 after the first discharge of blood, the female passes several months without 

 another period, when the second flow takes place and the menses then be- 

 come regular. In a condition of health the periods recur every month, 

 until they cease, at what is termed the change of life. In the majority of 

 cases the flow recurs on the twenty-seventh or the twenty-eighth day ; but 

 sometimes the interval is thirty days. As a rule, also, utero-gestation, lacta- 

 tion, and severe diseases, acute and chronic, suspend the periods ; but this 

 has exceptions, as some females menstruate regularly during pregnancy, and 

 it is not very uncommon for the menses to appear during lactation. 



Removal of the ovaries, especially when this occurs before the age of 

 puberty, usually is followed by arrest of the menses. It is a well known fact 

 that animals do not present the phenomena of heat, after extirpation of the 

 ovaries. Raciborski has quoted cases of this operation in the human subject, 

 in which the menses were arrested ; but this rule does not appear to be abso- 

 lute, as Storer has reported at least one case, in which menstruation contin- 

 ued with regularity for more than a year after removal of both ovaries. 

 Thomas, in three cases of removal of both ovaries from menstruating 

 women, which he followed for five and a half months to two years and 

 eleven months after the operation, noted no return of menstruation ; but in 

 one case, nearly six months after the operation, the patient had " a bloody 

 discharge from the vagina and all the symptoms accompanying the men- 

 strual function." Other cases of this kind are on record. 



When a cow gives birth to twins, one a male and the other apparently a 

 female, the latter is called a free-martin and generally has no ovaries. John 

 Hunter, in his paper on the free-martin, gave a full description of this 

 anomalous animal and stated that it does not breed or show any inclination 

 for the bull. In an examination of a free-martin, raised and killed by the 

 late Prof. James R. Wood, in 1868, the uterus was found rudimentary and 

 there were no ovaries (Flint). 



A menstrual period presents three stages : first, invasion ; second, a san- 

 guineous discharge ; third, cessation. 



The stage of invasion is variable in different females. There is usually, 

 anterior to the establishment of the flow, more or less of a feeling of general 

 malaise, a sense of fullness and weight in the pelvic organs, accompanied 

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