982 THE PHYSIOLOGY OF REPRODUCTION. 



seem to be sufficient to have any distinct influence on the body 

 metaboHsm. In regard to blood-pressure the statement is fre- 

 quently made that there is a fall at or during the menstrual flow, 

 but some observers fail to get this result and, in any case, it is not 

 very extensive.* On the whole, the experimental evidence thus 

 far obtained does not seem to indicate any very significant altera- 

 tion in the bodily functions as a result of menstruation. 



The Passage of the Ovum into the Uterus. — The means by 

 which the ovum gains entrance to the Fallopian tubes has given 

 rise to much speculation and some interesting experiments. It 

 was formerly believed (Haller) that at the time of ovulation the 

 fimbriated end of the Fallopian tube is brought against the ovary, 

 the movement being due to a congestion or a sort of erection of the 

 fimbriae. This movement has not been observed, and, as experi- 

 ments show that small objects introduced into the pelvic cavity are 

 taken up by the tubes, it is believed that the cilia upon the fimbriae 

 and in the tubes may suffice to set up a current that is sufficient 

 to direct the movements of the ovum. Attention has been called 

 to the fact that in animals with a bicornate uterus the ova may 

 be liberated from the ovary on one side, as shown by the presence 

 of the corpora lutea, while the embryos are developed in the horn 

 of the other side. As further evidence for the same possibility of 

 migration it has been shown that the ovary may be excised on one 

 side and the horn of the uterus on the other and yet the animal may 

 become pregnant after sexual union. It would seem probable, 

 therefore, that the ovum is discharged into the pelvic cavity and 

 may be caught up by the ciliary movements at the end of the tube 

 on the same side, or may traverse the pelvic cavity in the narrow 

 spaces between the viscera and be received by the tube on the 

 other side. Such a view explains the possible occurrence of true 

 abdominal pregnancies, and suggests also the possibility that ova 

 may at times fail to reach the uterus at all and may undergo de- 

 struction and absorption in the abdominal cavity. In some of 

 the lower animals — the dog, for example — provision is made for 

 the more certain entrance of the ova into the tubes by the fact 

 that the latter end in connection with a membranous sac of peri- 

 toneum which envelopes the ovary. The sexual fertilization of the 

 ovum is supposed to take place shortly after its entrance into 

 the Fallopian tube, since spermatozoa have been found in this 

 region, and the fertilized ovum, before reaching the seat of its im- 

 plantation in the body of the uterus, has begun its development. 

 By the act of coitus the spermatozoa are deposited at the mouth 

 of the uterus, whence they make their way toward the tubes, 



* King, "American Journal of Physiology," 34, 203, 1914; also Mosher, 

 "Johns Hopkins Hospital Bulletin," 12, 178, 1901. 



