CHANGES IN THE OVARY 139 



This suggestion receives some support from an experiment 

 by Clark/ who caused the rupture of a Graafian folhcle artificially 

 in a freshly removed ovary by injecting oarmins gelatine into 

 the vessels and so raising the ovarian blood pressure. 



The causes which determine the rupture of the Graafian 

 folhcle are also discussed by Heape,^ who is of opinion that 

 this is brought about in the rabbit by the stimulation of erectile 

 tissue, and not simply as the result of internal pressure arising 

 from increased vascularity or a greater quantity of liquor folhcuh.^ 

 In this animal the process must be due to a nervous reflex, in- 

 duced by the act of copulation. As has been shown above, in 

 those animals in which the ova are discharged spontaneously, 

 this usually occurs during oestrus, and not during the prooestrum 

 when the congestion of the generative tract is at its height. 



Harper's experiments * on the fertihsation of the pigeon's egg 

 elucidate the question somewhat further. This author writes as 

 follows : " When a pair [of pigeons] ready for mating is put 

 together, egg-laying ordinarily ensues at the end of a rather 

 definite period, at the least eight days. The female functions 

 are held in abeyance till the proper stimulus is received from a 

 mate.^ The maturing of the egg is so exclusively a female 

 function that it seems odd at first thought that an apparent 

 exception should occur to the rule. Of course, we know that 



struation, oestrus, or coitus. On the other hand, there is evidence that 

 ovulation is intimately associated with the occurrence of the sexual orgasm 

 in certain instances^ Thus Galabin records a case of a woman who married 

 under the age of twenty, and lived in married life with two husbands in 

 succession, and who, when she had passed the age of forty, experienced the 

 sexual orgasm in coitus for the first time, and from that day dated her first 

 and only pregnancy (Manual of Midwifery, 6th Edition, London, 1904). The 

 orgasm (which is characterised by the erection of the clitoris, accompanied by 

 certain sensations) is not necessary for conception, for pregnancy often occurs 

 in women who are " impotent." 



' Clark, " The Origin, Development, and Degeneration of the Blood-Vessels 

 of the Human Ovary, " Johns HopTcins Hospital Reports, vol. ix. , 1900. 



2 Heape, " Ovulation," &c., Proc. Roy. Soc, B., vol. Ixxvi., 1905. 



' It has been suggested that the follicle may rupture as a result of the 

 breaking down of the blood-vessels in its wall, and the consequently increased 

 pressure due to the bleeding into the cavity. See Heape. 



* Harper, "The Fertilisation and Early Development of the Pigeon's 

 Egg," Amer. Jow. of Anat., vol. iii., 1904. 



' In the common fowl, and probably in most other birds, ovulation takes 

 place independently of the male. 



