290 MONTGOMERY. [Vol. XV. 



1883. 



Balbiani ('83) renewed his observations on the egg of Geophilus 

 longiconiis, making several emendations. In very young eggs 

 there are two or numerous nucleoli, in larger eggs only one large 

 one, containing one or several vacuoles. In his previous paper 

 referred to, he assumed that the double tubular structure in 

 these eggs served for the purpose of an intraovular circulation ; 

 but in the present paper he offers another explanation: that 

 the double tubular structure later develops into a knotted cord, 

 the distal portion of which then divides into irregular frag- 

 ments, which become scattered through the yolk ; and then each 

 of these fragments, with the exception of one which becomes 

 the "noyau vitellin," differentiates into cytoplasm, nuclear and 

 nucleolar substance, and then represents a cell of the follicular 

 epithelium. 



Van Bemmelin ('83) states of the eggs of Brachiopoda : " Sie 

 haben meist zwei Kernkorperchen, die enganliegend und stark 

 lichtbrechend sind. Ausser diesen nimmt man oft noch mehrere 

 lichtbrechende Kugelchen in dem gefarbten Inhalte der Eikerne 

 wahr. Von Boraxkarmin werden sowohl diese Korperchen als 

 die Nucleoli stark gefarbt." (Certain of his figures show one 

 of the nucleoli imbedded in another.) 



Van Beneden ('83), ovum of Ascaris megalocephala : there is 

 a single " corpuscle germinatif," which contains all the chro- 

 matin of the nucleus, and is contained within a special portion 

 of the nucleus termed the " prothyalosome "; from one to three 

 "pseudonucl6oles" also occur in the nucleus, but they play no 

 important part in the maturation of the egg. 



Fol ('83a), egg of Ciona intestinalis : there is here one large, 

 very refractive nucleolus containing a number of vacuoles 

 which he believes are artefacts, since they cannot be found in 

 the living egg, though their appearance after the action of 

 reagents would show that the substance of the nucleolus is 

 chemically not homogeneous. The nucleolus consists of a more 

 refractive cortical substance, and of a less refractive, clearer 

 medullary portion ; in the latter, the vacuoles are produced. 

 Fol maintains that the follicle cells arise by budding from the 



