76 LEO LOEB. 



probable that the growth of the decidua perhaps in combination 

 with the growth of the embryo prolongs directly or indirectly 

 the life of the corpora lutea during pregnancy. Thus far ex- 

 periments, which we have carried out in order to decide this 

 question, have shown that the presence of living and growing 

 deciduomata prolongs the sexual period; furthermore that preg- 

 nancy prolongs the life of the deciduomata. Further investiga- 

 tion will decide whether or not these effects are exerted indirectly 

 by means of the corpus luteum. 



5. Our experiments render it certain that the structures which 

 we found in a considerable number of guinea pigs and which we 

 formerly interpreted as early stages of parthenogenetically 

 developed pregnancies in the ovaries of guinea pigs really represent 

 a relatively far going parthenogenetic development of ova which 

 may lead to the formation of embryos in the germ layer stage 

 which however usually leads merely to the formation of an em- 

 bryonal placenta probably as a response of the developing ovum 

 to the influence exerted by the contact with the surrounding 

 host tissue. We show furthermore the significance these findings 

 have for the interpretation of the teratomata and chorionepi- 

 theliomata of the germinal glands. 



6. The embryonal wander cells destroy outside as well as within 

 the wall of the uterus bloodvessels of the surrounding host tissue 

 in the ovary as well as in the peritoneal connective tissue and 

 they thus cause hemorrhages in the surrounding host tissue. 



