GERMINAL VESICLE AND FIRST EMBRYONIC NUCLEUS. 153 



Contributions to the History of the Germinal Vesicle, 

 and of the First Embryonic Nucleus. By Edouard 

 VAN Ben EDEN, Professor in the University of Liege. 

 (With Plate XIII.) 



I HAVE had the honour of presenting to the Academy a 

 summary exposition of the results of my researches on the 

 maturation of the ovule, the fecundation and earliest phe- 

 nomena in the embryonic development of the rabbit, up to 

 the moment of the appearance of the primitive streak more 

 especially. I have made known those of my researches 

 which establish the disappearance of the germinal vesicle, the 

 formation of the directive bodies {Richtungshldschen of Fritz 

 Miiller), and the appearance of the first embryonic nucleus. 

 The recent publication of the researches of Auerbach,^ 

 Biitschli,^ and Strasburger,^ on the formation and division of 

 the nuclei of cells, led me, in the course of my researches on 

 the development of mammalia, to investigate very specially how 

 the first nucleus of the embryo appears and how cells multiply 

 in the embryonic laminse. Long before I became acquainted 

 with these researches, I had observed that the germinal vesicle 

 of the rabbit disappears, independent of fecundation, and 

 that the disappearance of this element is the indication of the 

 complete maturity of the ovum. 



At the very moment when I was completing the drawing 

 up of my preliminary communication^ on the maturation of 

 the egg, its fecundation and development in the rabbit, 

 there appeared in Germany an important memoir by Oscar 

 Hertwig^ on the formation, fecundation, and division of the 

 egg of an echinoderm belonging to the order Echinida, 

 Toxopneustes lividus. M. Hertwig and I, endeavouring to 

 solve the same problems, but having chosen for our researches 

 animals belonging to different groups, have arrived at 



1 Leopold Auerbach : 'Organologiscbe Studien/ Breslau, 1874. 



' 0. Biitschli : " Vorlaufige Mittheilung iiber Untersuchungen betrefFend 

 die ersten Entwickeluugsvorgange im Befruchteten Ei vou Nematoden und 

 Schnecken," ' Zeitsch. fiir Wiss. Zoologie,' Bd. xxv. 0. Biitschli : " Vor- 

 laufige Mittheilung einiger Resultate von Studien iiber die Conjugation der 

 Infusorien und die Zelltheilung," ' Zeitsch. fiir Wiss. Zoologie/ Bd. xxv, 



^ Eduard Strasburger : ' Ueber Zellbildung und Zelltheilung,' Jena, 1875. 



* Edouard van Beueden, " Le maturation de I'ceuf, la fecondation et les 

 Premieres Phases du Developement Embryonnaire des Mammiferes d'apres 

 des recherches faites chez le Lapin," (Communication preliminaire), ' Bull. 

 de I'Acad. Roy. de Belgique,' 2e serie, t. xl, 1875. 



* Oscar Hertwig, " Beitrage zur Kenntniss der BUdung, Befruchtung, 

 und Theilung des Thierischen Eies," ' Morphologisches Jahrbuch von 

 C. Gegenbauer.' 



