306 ARTHUR WILLIAM MEYER. 



siderable degree to this fact. Jones and Austrian, '07, found, for 

 example, that the livers of young pig embryos contain no nulein 

 enzymes, but that these increase as fetal development proceeds. 

 The latter finding seems to be confirmed also by data given by 

 Mendel and Leavenworth, '08, although these investigators 

 found enzymes present at all ages. Schlesinger, '03, who was, 

 I believe, the first to establish the occurrence of autolysis in 

 retained human fetuses, also found that it varied with age and 

 other conditions. 



Since the chorionic villi do not undergo autolysis first, the 

 conclusion that heterolysis is not an important factor in lysis of 

 the conceptus, also seems justified. If enzymes of decidual 

 origin played any large part in the process of lysis of the con- 

 ceptus, one might, I presume, expect to find instances in which 

 at least portions of the chorionic vesicle underwent lysis al- 

 though the embryo itself remained quite unaffected. This, 

 however, never seems to be the case and the same thing holds 

 for the placenta and the chorionic vesicle and also for the decidua. 

 That heterolysis probably plays only a very subsidiary role is 

 indicated also by the fact that autolysis takes place in tubal 

 implantations as well, and still more convincingly by its occur- 

 rence in ovarian implantations, as illustrated especially by 

 the case of Holland, 'n, and by other cases . referred to by 

 Meyer, and Wynne '19, in which the escape of portions of the 

 conceptus from the ovarian implantation cavity could be wholly 

 excluded. One reason for prolonged preservation of the decidua 

 no doubt lies in the fact that it as a whole or at least in large 

 part retains vitality because it remains quite undisturbed in its 

 vascular relations. 



REFERENCES. 

 Curtis, A. H. 



'15 Experiments in the Production of Abortion and Labor by use of Placental 



Extracts. Surg. Gyn. and Obst., Vol. 20. 

 Fraenkel, E. 



'03 Ueber "missed labor" und "missed abortion." Samml. klin.Vortrage, 



Volkmann N.F. Gyn. 

 Fraenkel, L. 



'03 Die Function des Corpus luteum. Arch. f. Gyn., Bd. 68. 

 Henneberg, B. 



'03 Experimented erzeugte Riickbildungsvorgange am graviden Saugetieru- 

 terus. Anat. Anz., Bd. 24. 



