36 LEO LOEB. 



after the last operation the absence of placentomata in -the 

 uterus. Mitoses are, however, present in the surface epithelium 

 and sometimes also in the gland cells. Twice we found a few 

 mitoses in the connective tissue of the mucosa which may either 

 be myxoid in character or show the usual fibrillar character. 

 Just as early extirpation of the corpora lutea prevents the ex- 

 perimental placentomata, so does extirpation of the ovaries 

 have the same effect and we may, therefore, assume that also 

 in this case extirpation of the ovaries is effective through the 

 accompanying removal of the corpora lutea. 



Through lack of the corpora lutea the sensitizing or preparing 

 substance is removed which in combination with the mechanical 

 factors causes the predecidual cell proliferation and the develop- 

 ment of the placentomata. Under these conditions the cuts do 

 not cause proliferation in the connective tissue of the mucosa. 



If we extirpate the ovaries six to seven days after copulation 

 and at the same time make incisions into the uterus, we may find 

 on examination ten to thirteen days later either none (two 

 cases), or very small placentomata (in one case in which the 

 examination had been made thirteen days after excising the 

 uterus). In the last mentioned case, about one half of the pla- 

 'centoma had become necrotic, the remaining part showed a 

 hyaline character with nuclei embedded in a homogeneous glassy 

 matrix. At one place there were still visible in the placentoma 

 parts of the fetal placenta in the form of syncytiomatous vessels 

 passing into the maternal tissue and also in the surrounding fat 

 tissue. The extirpation of the ovaries caused in this case a very 

 incomplete and retarded development of the ovum; a similar 

 retardation in the development of the ovum we found also in a 

 case of extrauterine pregnancy and a similar effect may be ob- 

 served after extirpation of the corpora lutea. Under these 

 conditions the soil is evidently not favorable for the development 

 of the ovum. 



In three cases in which the ovaries were extirpated eight days 

 or almost eight days after copulation and at the same time in- 

 cisions were made into the uterus, very small placentomata 

 developed in two cases and only a trace of a placentoma in one 

 case. On examination eleven days after the operation, a partial 



