370 THE PHYSIOLOGY OF REPRODUCTION 



during pregnancy fully confirm those of Fraenkel. It must be 

 pointed out, however, that there is no evidence that the corpus luteurn 

 governs the fixation of the embryo in any other than the indirect 

 sense implied in the supposition that the secretion elaborated by that 

 organ acts as a stimulus which excites the uterine mucosa to undergo 

 the necessary hypertrophy. In this general sense, also, it is probably 

 true that the luteal secretion (or, at any rate, the secretion of the 

 ovary) assists in nourishing the embryo during the first stages of 

 pregnancy, since there is every reason for concluding that it helps to 

 maintain the raised nutrition of the uterus. It has been shown that 

 the presence of the ovaries is not essential for the continuance of 

 pregnancy in the later stages, when the corpora lutea are in process 

 of degeneration. It would seem not unlikely, therefore, that the 

 atrophic changes (fibrosis) which take place in the decidua serotina, 

 or maternal , placenta, in the later part of the gestation period are 

 directly correlated with the degeneration of the corpus luteum. 1 



Cases have been recorded by Essen-Moller, 2 Graefe, 3 and Flatau, 4 

 in which pregnancy was not interrupted by double ovariotomy in 

 women when performed in the early stages of pregnancy. These 

 cases .are undoubtedly very exceptional, and it seems legitimate to 

 conclude that a small portion of an ovary, probably containing luteal 

 tissue, was left behind accidentally at the time of the operation. So 

 able and experienced an operator as Bland Sutton 5 has recently 

 testified to the extraordinary difficulty experienced in removing the 

 whole of the ovarian tissue in ovariotomy, and the distinguished 

 French obstetrician, Lucas-Champonniere, 6 has expressed himself in 

 the same sense, so that there is nothing unreasonable in the assumption 

 that the operation of removal is sometimes incomplete when performed 

 on pregnant women. 



Daels 7 has recorded a large series of experiments upon guinea- 

 pigs and rats in which he found that bilateral castration invariably 

 interrupted the course of pregnancy during rather more than the 

 first half of its duration. In control experiments portions of 



1 It has been suggested that the co.rpus luteum contributes an essential 

 factor in the nourishment of the embryo through the trophoblast, and that it 

 consequently ceases to be functional in the later part of pregnancy when the 

 trophoblast is superseded by the allantoic placenta. See Andrews, loc. cit. 



2 Essen-Moller, " Doppelseitige Ovariotomie im Anfange der Schwanger- 

 schaft," Central. f. Gynak., vol. xxviii., 1904. 



3 Graefe, "Zur Ovariotomie in der Schwangerschaft," Zeitsch. f. Geb. >'. 

 Gynak., vol. Ivi., 1905. 



4 Flatau, "Ueber Ovariotomie wahrend der Schwangerschaft," Arch. f. 

 Gynak , vol. Ixxxii., 1907. 



5 Bland Suttori, "A Clinical Lecture on the Value and Fate of Belated 

 Ovaries," Medical Press, vol. cxxxv., (31st July) 1907. 



Lucas-Champonniere, " Sur une Observation de Graffe Ovarienne Suivie 

 de Grossesse," Jour, de Me'd. et de Ctiirurgie Pratiques, vol. Ixxviii., (May) 1907. 



7 Daels, " On the Relations between the Ovaries and the Uterus," Surgery, 

 Gynaecology and Obstetrics, vol. vi., 1908. 



