710 OVULATION AND MENSTRUATION. 



periods of osstruation in the lower animals. Their general resemblance 

 to these periods is very evident. Like them, they are absent in the 

 immature female, and begin to take place only at the period of puberty, 

 when the aptitude for impregnation commences. Like them, they recur 

 during the child-bearing period at regular intervals, and are liable to 

 the same interruption by pregnancy. Finally, their disappearance 

 corresponds with the cessation of fertility. 



The periods of oestruation, in many of the lower animals, are accom- 

 panied with an unusual discharge from the generative passages, fre- 

 quently more or less tinged with blood. In the human female the 

 bloody discharge, though more abundant than in other instances, differs 

 only in degree from that in many species of animals. 



But the most complete evidence that the period of menstruation is in 

 reality that of ovulation, is derived from the results of direct observa- 

 tion. A sufficient number of instances have been observed to show that 

 at the menstrual epoch a Graafian follicle becomes enlarged, ruptures, 

 and discharges its egg. Cruikshank 1 noticed such a case so long ago 

 as 1797. Ne'grier 2 relates two instances in which, after sudden death 

 during menstruation, a bloody and ruptured Graafian follicle was found 

 in the ovary. BischofT 3 speaks of four similar cases, in three of which 

 the follicle was just ruptured, and in the fourth distended, prominent, 

 and ready to burst. Coste 4 met with several of the same kind. Michel 5 

 found a follicle ruptured and filled with blood in a woman who was 

 executed for murder while the menses were present. Two instances 

 are reported by Letheby, 6 in women who died while under observation 

 in the London hospitals, in one of which he succeeded in finding the 

 ovum, which had been expelled from the ovary, in the contents of the 

 corresponding Fallopian tube. We have also seen a Graafian follicle 

 recently ruptured and filled with blood, in a woman who died on the 

 second day of menstruation. 



Ovulation. accordingly, in the human female, accompanies and forms 

 a part of menstruation. As the menstrual period comes on, a conges- 

 tion takes place in nearly the whole of the generative apparatus ; in the 

 Fallopian tubes and the uterus, as well as in the ovaries and their 

 contents. One of the Graafian follicles is especially the seat of vascular 

 excitement It becomes distended by the fluid accumulated in its cavity, 

 projects from the surface of the ovary, and is finally ruptured ; the 

 process taking place essentially in the same manner as in the mammalian 

 animals. 



It is not certain at what particular period of the menstrual flow the 

 rupture of the follicle and discharge of the egg take place. According 



1 Philosophical Transactions. London, 1^97, p. 135. 



2 Recherches sur les Ovaires. Paris, 1840, p. 78. 



3 Annales des Sciences Natnrelles. Paris, Aout, 1844. 



4 Histoire du DSveloppement des Corps Organises. Paris, 1847, tome i. p. 221. 

 6 American Journal of the Medical Sciences. Philadelphia, July, 1848. 



6 Philosophical Transactions. London, 1852, p. 57. 



