644 REPRODUCTIVE ORGANS. 



coincidence, however, is by no means necessary or invariable, since 

 ovulation undoubtedly proceeds independently of menstruation. 

 Other authorities regard the intervals between periods of ovula- 

 tion as very irregular. J. Bland Button, in his Surgical Diseases 

 of the Ovaries and Fallopian Tubes, says : " In the ovary of the 

 human fetus ova ripen, form follicles, and undergo suppression 

 during the last month of intra-uterine life. The life of the human 

 ovary may be divided into the following periods of activity and 

 repose : The first period extends from the seventh month of intra- 

 uterine life to the end of the first year. Ova ripen in such abund- 

 ance that in some cases a marked diminution in the number of the 

 ova is appreciable at the second year after birth. To this succeeds 

 a period of comparative repose, terminating at the tenth or twelfth 

 year ; then the ripening of the ova is again easily detected, and 

 goes on independently of menstruation, even after the accession of 

 the climacteric." 



In an uncertain proportion of instances the ova find their way 

 into the Fallopian tube. The mechanism by which this is accom- 

 plished is still a matter of doubt. One theory maintains that the 

 fimbriated extremity is so approximated to the ovary as to bring 

 the ostium abdominale against the part at which the Graafian 

 vesicle is about to rupture, and that the escaping ovum thus enters 

 the tube. This approximation is by some writers supposed to be 

 due to an engorgement of the fimbriated extremity by blood, thus 

 causing its erection and approximation, but the absence of erectile 

 tissue disproves this theory. Tait found, in certain cases upon 

 which he operated, the tube grasping the ovary, and he attributed 

 this action to muscular fibers in the tube which develop at the 

 period of puberty and which atrophy at the menopause, so that 

 ova can enter the tube only during the active life of these fibers, 

 and then, and then only, can pregnancy take place, though both 

 before puberty and after the menopause ovulation may occur, the 

 ova under these circumstances falling into the abdominal cavity, 

 where they disintegrate. According to this theory, if ovulation takes 

 place and the tube does not grasp the ovary, the ovum when dis- 

 charged does not enter the tube, but falls into the abdominal cavity. 



The second theory is that this grasping of the ovary by the 

 tube does not occur, but that the ovum is carried into the ostium 

 abdominale by the current created by the ciliated epithelium lining 

 the fimbriae. 



This latter theory is the one generally accepted at the present 

 time. Indeed, facts are accumulating to show that this current is 

 sufficiently powerful to carry an ovum from one ovary to the tube 

 of the opposite side. Kelly removed a diseased left ovary and 

 right tube from a woman who, fifteen months later, was delivered 

 of a child at term. In this instance the ovum must have come 

 from the right ovary and been carried to the uterus through the 



