SUPPLEMENT 



(referred to AT p. IG) 

 ON THE SIGNIFICATION OF THE GERMINAL VE8ICLE. 



When treating of the different parts of the ovum, in the 

 foregoing work, it was found impossible to give a positivi 

 solution to the question as to whether the germ-vesicle was a 

 young cell or the nucleus of the yelk-cell. Most of the facts 

 before us were in favour of the latter view ; but if this were the 

 correct one, the yelk-cell ought to be developed around the 

 previously existing vesicle in such manner, that it in the 

 first instance closely encompassed the latter, and afterwards 

 became gradually expanded. This decisive observation was 

 wanting, and the researches communicated by R. Wagner, in 

 his ' Prodromus/ rather tended to show that, in the formation 

 of the ovum around the germinal vesicle, the membrane was 

 not formed immediately around the vesicle, but that it inclosed 

 at the same time a quantity of the granular mass in which the 

 germ-vesicle lies. I was not at that time acquainted with a 

 work of Wagner's, which contained the facts necessary to a 

 solution of the question, viz. his f Bcitrage zur Geschichte 

 der Zeugung unci Entwickelung., Erster Bcitrag:' from the 

 ' Mathematisch-physikalischen Klasse der Konigl. Baierschen 

 Acad, der Wissenschaften in Munchen/ Speaking of the 

 ovaries of insects, Wagner says, at page J 5 : — " At the spot 

 where the oviduct widens, the granular mass, which resembles 

 the vitelline mass, becomes more plentiful; the separate germ- 

 vesicles seem to be imbedded in it. I have so represented it 

 in the ' Prodromus/ fig. 18. Lately, however, it has appeared 

 to me, as though the germ-vesicles with their germinal spots 

 were actually already surrounded by a chorion and a perfectly 

 pellucid yelk." The accompanvin- illustration from Agrion 

 virgo exhibits clearly how thai which Wagner calls chorion. 



