14 



The S p i r a 1 A s t e r s (Mark). In eggs found floating in the ova- 

 rian fluid, the germinal vesicle is metamorphosed into a centrally si- 

 tuated Archiamphiaster . The rays of the stars are short and feeble. 

 The spindle seems not to terminate in points at the centres of polar 

 areas, asHertwig represents. In fact, the spindle-rays appear to 

 differ in no essential way from the other rays belonging to the asters 

 as F o 1 , 13 o b r e t z k y , Whitman, and Mark have observed. 



In eggs examined just after laid , the Archiamphiaster presents 

 quite a different aspect. The astral rays have grown considerably in 

 length, often extending to the periphery. They describe nearly uniform 

 curves, so that they have a spiral arrangement. When viewed 

 from sides the spiral of both are always dextrally curved. If however 

 either star is viewed from above, the spiral will be sinistral. This may 

 be accounted for by supposing that the rays have a double curvature. 



Such a spiral arrangement of the astral rays has been entirely over- 

 looked, except by Dr. Mark of Harvard University, who was the first 

 to describe it in Limax. 



The spindle has also grown in size and the central thickened zone 

 (Kernplatte) is very distinct. 



In a few minutes, as the Archiamphiaster travels toward the peri- 

 phery, the astral rays become shorter and lose their spiral sweep. 

 Tokio, Japan, Sept. 22nd, 1881. 



3. Encore un mot sur le Nephridium, et la Cavité du Corps 

 des Trématodes et des Cestodes. 



Réponse à M. RayLankester. 

 Par Edouard Van Beneden, Professeur à l'Université de Liège. 



Dans un note inséré dans le No. 85 de ce Journal (13 Juin 1881) 

 M. Lank est er a élevé une réclamation de priorité contre mon élève 

 J. F rai pont. Il y affirme que les conclusions formulées par ce der- 

 nier, à la suite de ses études sur l'appareil urinaire des Trématodes et 

 des Cestodes s'identifient avec les idées développées par lui Dan- 

 kest er dans deux publications successives : 1) On the primitive Cell- 

 layers of the Embryo, 2) Notes on Embryology. Voici en quels termes 

 il formule sa revendication: »As a matter of fact (though I had not suc- 

 ceeded in observing the exceedingly important facts made known by 

 M. P'raipont) 



I had been led by investigation of various species 

 of Cer caria and of the transparent Aspiclog aster and of 

 Caryophylleus (LeucKart's Archigetes) to the theore- 



