167 



tence of a plasmodiblastic, as distinct from a cytoblastic layer 

 of the trophoblast; but be appears to have considered that the 

 former was an exceedingly transitory tissue, and that the syn- 

 cytium of the placenta was formed from the endothelium of the 

 superficial maternal eapillaries. 



To judge merely from the very excellent figures by which they 

 are illustrated Maximow's two papers are far move deserving of 

 careful consideration than the publications of the authors already 

 quoted. With regard to the degeneration of the uterine epithe- 

 lium, and the formation of the syncytium liniDg the maternal 

 blood spaces of the placenta from the plasmodial layer of the 

 trophoblast he fully corroborates Duval's account. His description 

 of the latter process is however more detailed; the superficial 

 eapillaries possess only a very thin endothelium, so thin that 

 their lumen is actually bounded in many places by the surrounding 

 glycogenic cells; the endothelial cells may also become glycogenic. 

 By the enlargement and separation of these cells the walls of 

 the eapillaries are loosened, and the coutained blood extravasted 

 into lacunae of the surrounding trophoblast. The followiug remarks 

 of his have such an important hearing on the theory of placenta- 

 formation, that I venture to quote them in f uil. 'Jedenfalls muss 

 'man von einem 'Einwachsen' des Ectoderms in die Schleimhaut 

 'nur mit Vorsicht sprechen. Es muss natürlich in den Anfaugs- 

 'stadien der Placentation ein actives Eindringen des embryonalen 

 'Gewebes in das mütterliche angenommen werden, doch dauert 

 'solches nicht lange fort — eigentlich auch nur bis zum Moment 

 'wo sich durch Extravasation die ersten Blutraume im Syncytium 



'bilden Die Ectoplacenta entwickelt sich 



'eben uicht auf Kosten von Einwucherung in die Schleimhaut, 

 'soudern hauptsachlich durch selbstandiges Wachstum des embryo- 

 'nalen Gewebes' (32 p. 726). With regard to the endovascular 

 plasmodium Maximow is not able to confirm Duval's statements. 

 The structure in question is apparently merely due to a hyper- 

 trophy of the endothelium, which is subsequently infiltrated with 

 leucocytes and undergoes degeneration. 



