138 THE PHYSIOLOGY OF REPRODUCTION 



of the ova. Some authors express the belief that ovulation 

 occurs before menstruation, others that it takes place during 

 that process, and others again that it follows menstruation. 

 Hergesell 1 has lately adduced evidence which, in his opinion, 

 points to the conclusion that ovulation precedes menstruation, 

 but the occurrence of corpora lutea of uncertain age in the ovary 

 cannot be regarded as supplying definite proof. There are 

 reasons, on the other hand, for concluding that, primitively at 

 any rate, the most usual period for ovulation in the human 

 female was during a definite oestrus following a procestrum, as 

 in many of the lower Mammals ; for the period of most acute 

 sexual feeling is generally just after the close of the men- 

 strual period (see p. 69), while, according to Raciborsky, this 

 is also the commonest season for fertile coition. 2 Moreover, 

 the facts narrated by Bryce and Teacher, in a recent memoir 

 on the early development and embedding of the human ovum, 

 render it extremely probable that the ovum described had 

 been discharged shortly after the cessation of the last men- 

 struation. 3 



With regard to the question as to whether any special 

 stimulus is necessary to induce ovulation in women, Oliver 4 is 

 of opinion that whereas it sometimes may occur spontaneously, 

 it is more than probable that it " may be and often is accelerated 

 by coitus," since at this time there is " an increased determina- 

 tion of blood to the whole genital tract." 5 



1 Hergesell, "Das zeitliche Verhalten der Ovulation zur Menstruation." 

 Inaug. Diss., Leipzig, 1905. 



8 Raciborsky, Traite de Menstruation, Paris. 



3 Bryce and Teacher, Contribution to the Study of the Early Development 

 and Embedding of the Human Ovum, Glasgow, 1908. 



4 Oliver, "A Study of Fertilisation with Reference to the Occurrence of 

 Ectopic Pregnancy," Edin. Med. Jour., vol. liv., 1902. 



6 Pregnancy, and therefore ovulation, have been known to take place 

 before the onset of menstruation. Pregnancy may also occur during amenor- 

 rhoea (e.g. at the commencement of the menopause) and during the lactation 

 period, when menstruation is often in abeyance. Again, it is stated that 

 ovulation has been noted during infancy, before any of the other indications 

 of puberty have been observed (Webster, " The Biological Basis of Menstrua- 

 tion," Montreal Medical Journal. April 1897). Further, it will be shown below 

 (p. 348) that the ovaries can maintain their normal functions after the 

 removal of the uterus. It would seem, therefore, that ovulation may occur 

 spontaneously in women, and is not necessarily connected with either men- 



