592 HEEBEET M. EVANS 



this ovulation, however, having occurred at a very considerable time in- 

 terval before the expected menstruation. 21 Mall and Triepel have shown 

 that in cases with a reliable history the copulation age of embryos is 

 always about ten days less than the menstrual age, which is the term 

 used for the time elapsing from the last normal period. 



There are thus fundamental analogies between the sex cycle of the 

 other mammalia and of man, although in man an oestrous period cannot 

 properly be said to exist nor can a true menstruation be said to occur in 

 the other mammalia. In both cases certain ante-ovulatory ovarian changes 

 probably the ripening follicles are clearly associated with certain 

 other changes in the reproductive system and, again, in both cases certain 

 postovulatory ovarian changes the production of corpora lutea are asso- 

 ciated with certain further changes in the reproductive system. We have 

 thus to recognize not only that there is a primary role of the gonad in the 

 cyclic change of the genitalia but that specific tissue components of the 

 ovary produce specific effects on the genitalia. 22 In this field, further- 

 more, as in so many others, the study of certain pathological states serves 

 to strengthen the physiological conceptions which have been expressed 



21 This resolves the extensive discussions on this subject, which were participated 

 in by Kundrat and Engelmann, Siegmund, Loewenhardt and Reichert, all of whom 

 claimed that the fertilized egg "belonged" to the last normal menses and which led 

 Aveling in 1874 to give the first true interpretation of premenstrual swelling as pre- 

 gravid or implantation changes. Furthermore, although at the time he wrote few 

 early human embryos had been well investigated, Ahfeld was inclined to adopt the 

 above views, since the youngest "ova" known to him led him to declare that implanta- 

 tion had taken place by the time of the first missed period and so the ovum could not 

 belong to it. This view of the time of implantation has been supported by the study of 

 very early gestations in the last few years (Peters, Bryce and Teacher), but it cannot 

 lead us to declare that the development of the embryo was inaugurated quite so early 

 as coincidentally with the last normal period. 



22 The reader will observe that I have been unable to follow Schroeder. Aschner and 

 especially R. Meyer in the complete extent to which they ascribe all changes in the 

 ovary to the egg alone (see, for instance, R. Meyer: "'Das Ei in seinem Reifwerden 

 seinem Reifsein und seinem Tod beherrscht das ganze genitalgeschehen.") . Accord- 

 ing to Meyer, corpus luteum formation begins even in the intact follicle when the 

 egg ripening has reached a certain stage and hence quite regardless of follicular 

 rupture. Furthermore, he believes that the life of the corpus is also dependent upon 

 the life of the egg and that the former structure does not degenerate until the death 

 of the latter. Ruge, Seitz, Grosser and others have already challenged this idea, 

 expressing their belief that the human fertilized ovum cannot be regarded as living 

 almost two weeks after ovulation. Our more exact acquaintance with the conditions 

 in some of the mammalia would also seem to very clearly negate Meyer's contention. 

 Lams and Doorme have recognized an early time of degeneration of the tubal eggs in 

 the case of the guinea pig and the same is true for the white rat. The corpora lutea 

 certainly outlast the eggs and hence deserve to be regarded as possessing an inde- 

 pendent normal life span. The extent to which Meyer has pushed his theory would 

 appear consequently unjustifiable, but there is equally no doubt but that if the eggs 

 be fertilized there exists an hormonal effect (Fernwirkung) resulting therefrom, 

 whether by way of the corpus or not, for the so-called pregravid endometrium im- 

 mediately becomes a gravid one and even an immediately impending menstruation 

 necrosis is prevented. As we have previously shown, the studies of war pregnancies 

 have proven this. 



But we are acquainted with circumstances which prolong the life of a corpus 

 luteum other than those which could be contributed by the egg. A good example 

 of this is furnished by lactation. There is a prolonged function of the corpora lutea 



