NATURE AND CAUSES OF MENSTRUAL FLUX. 893 



to be nearly or quite identical with ordinary blood ; but in its passage through 

 the vagina, it becomes mixed with the acid mucus exuded from its walls, 

 which usually deprives it of the power of coagulating. If the discharge 

 should be profuse, however, a portion of its fibrin remains unaffected, and 

 clots are formed. In cases in which, by the death of women at this period, 

 an opportunity has been afforded for the examination of the lining membrane 

 of the uterus during menstruation, it is found to be unusually turgid with 

 blood, the veins in particular being much distended, and opening upon the 

 internal surface by capillary orifices, to which valvules are occasionally 

 found attached. 1 Hence it is scarcely correct to designate the menstrual , 

 flux as a "secretion;" although there is reason to think that it may carry 

 oft', besides blood, certain matters which would be appropriate to the forma- 

 tion of a Decidual membrane ( 751), but which, if not so employed, become, 

 excrementitious. The interval which usually elapses between the successive 

 appearances of the discharge, is about four weeks; and the duration of the 

 flow is from three to six days. There is great variety in this respect, how- 

 ever, among the inhabitants of different climates, and among individuals; in 

 general, the appearance is more frequent, and the duration of the flow 

 greater, among the residents in warm countries, and among individuals of 

 luxurious habits and relaxed frame, than among the inhabitants of colder 

 climes, or among individuals inured to bodily exertion. The first appear- 

 ance of the discharge is usually preceded and accompanied by considerable 

 general disturbance of the system, especially pain in the loins and a sense of 

 fatigue in the lower extremities; and its periodical return is usually attended 

 with the like symptoms, which are more or less severe in different individuals. 

 741. Much discussion has taken place respecting the causes and purposes 

 of the Menstrual flow ; and modern inquiries have thrown great light upon 

 them. The state of the female generative system, during its continuance, 

 appears to be analogous to the heat or periodic sexual excitement of the 

 lower animals; some of which have a sero-sanguinolent discharge at that 

 period, and among many of which the ova are entirely extruded by the 

 female before the spermatic fluid of the male reaches them, this occasion- 

 ally taking place even in Birds. There is good reason to believe that in 

 the Human female the sexual feeling becomes stronger at the period of 

 menstruation ; and it is quite certain that there is a greater aptitude for 

 Conception immediately before and after that epoch, than there is at any 

 intermediate period. Observations to this effect were made by Hippocrates, 

 and were confirmed by Boerhaave and Haller ; indeed, coitus immediately 

 after menstruation appears to have been frequently recommended as a cure 

 for sterility, and to have proved successful. This question has been made 

 the subject of special inquiry by M. Raciborski; who affirms that the ex- 

 ceptions to the rule that conception occurs immediately before or after, or 

 during menstruation are not more than 6 or 7 per cent. Indeed, in his 

 latest work on the subject, 2 he gives the details of fifteen cases, in which 

 the date of conception could be accurately fixed, and the time of the last 

 appearance of the cataraeuia was also known ; and in all but one of them, 

 the correspondence between the two periods was very close. Even in the 

 exceptional case, the catameuia made their appearance shortly after the co- 

 itus ; which took place at about the middle of the interval between the two 

 regular periods. When conception occurs immediately before the men- 

 strual period, the catamenia sometimes appear, and sometimes are absent; 

 if they appear, their duration is generally less than usual. The fact that 



1 See Whitehead, On Abortion and Sterility, pp. 13-37. 



2 Sur la Ponte des Mammiieres, Paris, 1844. See also Lancet, 1871, vol. i, p. 421. 



