Vol. XXVIII. February, 1915. No. 2. 



BIOLOGICAL BULLETIN 



AN EARLY STAGE OF AN EXPERIMENTALLY PRO 

 DUCED EXTRAUTERINE PREGNANCY AND 

 THE SPONTANEOUS PARTHENOGENESIS yf^^^^^^^^^h^ 

 OF THE EGGS IN THE OVARY OF /^ *''. \ 



THE GUINEA PIG.^ ( FEB 261915 / 



LEOLOEB. ^^onnH"-^^^" 



The observation on which I wish to report is of great interest 

 from several points of view. It explains the negative result of 

 our former attempts which aimed at producing experimentally 

 an extrauterine pregnancy in the guinea pig. It contributes to 

 the understanding of the mechanism of the sexual cycle and it 

 makes certain my previous conclusions, which formerly had only 

 been probable, concerning the fargoing parthenogenetic develop- 

 ment of ova in the ovary of the guinea pig, conclusions which our 

 previous studies had made very probable. In a great number of 

 previous experiments we made incisions in various parts of the 

 uterus of the guinea pig and at different times after copulation. ^ 

 Under these circumstances it certainly must often have happened 

 that fertilized eggs left the uterine cavity. But . extrauterine 

 pregnancy did in no case take place under such circumstances. 

 Even after ligation of the fallopian tubes we were not able to 

 observe the occurrence of an extrauterine pregnancy. This 

 latter observation is in accordance with some experiments of 

 Mandl and Schmidt.^ It was of interest to determine what was 

 the fate of the ova which left the lumen of the uterus and passed 

 into the peritoneal cavity after fertilization. An observation 



1 From the pathological laboratory of the Barnard Free Skin and Cancer Hos- 

 pital, St. Louis. 



2 Leo Loeb and John W. Hunter, University of Pennsylvania Medical Bulletin, 

 Dec, 1908. 



^Archivf. Gynaecol., 56, 1898. 



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