196 INTERNAL SECRETIONS OF THE OVARY 



problematical authenticity, but at the same time it is possible 

 that some at least are genuine. 



{e) MAINTENANCE OF PREGNANCY 



As pointed out in a previous section there can be little doubt 

 that the corpus luteum is necessary for the sensitization of 

 the uterus, and thus probably for the implantation of ova. 

 Authors are not agreed, however, as to how long the corpus 

 luteum continues to be essential for the maintenance of preg- 

 nancy. Fraenkel (211) came to the conclusion that it was only 

 required during the early stages and that subsequently the 

 corpus luteum could sometimes be removed with impunity. 

 Even so, Fraenkel's work showed that the corpus luteum was 

 necessary for some time after implantation had taken place, 

 and, therefore, it was not merely concerned with the sensitiza- 

 tion of the uterus. Marshall and Jolly (451) for the dog and the 

 rat, and Kleinhaus and Schenk (324) for the rabbit, came to the 

 same conclusion. Blair Bell (56) and Essen-Moller (181) report 

 clinical cases which suggest that in the human the removal of 

 the corpus luteum of pregnancy during the later stages may 

 produce no adverse effect. Ask-Upmark (46) has collected 

 similar instances. Herrick (290) found that in some cases 

 pregnancy would continue in the guinea-pig after double 

 ovariectomy. In spite of this large amount of evidence showing 

 that the corpus luteum is not essential during the later stages 

 of gestation, many authors have come to exactly the opposite 

 conclusion and find that the removal of the corpora lutea or 

 ovaries at any stage of pregnancy results in the termination of 

 gestation. Blair Bell and Hick (57), Hammond (264), Wey- 

 meersch (635), Mcllroy (430), and Dick and Curtis (155) have 

 reported that in the rabbit the removal of the ovaries during 

 pregnancy is inevitably followed by the abortion or reabsorp- 

 tion of the foetuses. Mulon (466) and Daels (151) state that 

 ovariectomy at any stage terminates pregnancy in the guinea-pig. 

 In the cow the removal of the corpora lutea was found by Hess 

 (298) , by Wester (634) , and by Schmaltz (547) to be incompatible 

 with the continuance of pregnancy. Similar results have been 

 described for the goat by Drummond- Robinson and Asdell (171) , 



