THE CELL DOCTRINE. 121 



prises the nuclear membrane, the nucleolus, and a 

 fibrillar stroma, which latter, in some instances, ex- 

 tends in a radial manner from the nucleolus. 



E. Van Beneden* saw a fine protoplasmic reticu- 

 lum in the large axial entoderm cell of Dicyema, 

 which (reticulum) exhibited slow spontaneous move- 

 ments. In the nucleus of the ripe ovum of Astero- 

 canihion rubens he also observed within the nuclear 

 membrane and beside the nucleolus a delicate net- 

 work of finely granular substance, which he calls 

 "nuclepplasma," including several " pseudo-nucleoli." 

 According to him the germinal vesicle of the ripe 

 ovum of the rabbit also contains a minute network. 



Arudt,t in 1876, distinguished in the nucleus a 

 homogeneous ground substance and elementary glob- 

 ules ; the former possesses a vesicular structure, and 

 incloses in its meshes the latter. 



W. FJemming,:]: in observations on the structure 

 of nuclei found in the membrane of the urinary blad- 

 der of Salamandra maculata, in 1876, saw a very deli- 

 cate and dense network of fibres uniformly pervading 

 the interior of the nucleus, and attached to the 

 nuclear membrane. This network, " Geriistformige 



* La maturation de I'oeuf, la fecondation et les premi&res phases 

 du dfiveloppement embryonaire des Mammiftres. Bui. de I'Acad. 

 Koyale de Belgique, 2 Ser., t. 40, 1875; also Contributions I. Phis- 

 toire de la vfesieule germinative et du premier noyau embryonaire, 

 in the same journal, January, 1876. 



■j- tjber den Zellkern, Sitzungsb., d. Medicin. Vereins zu Greifs- 

 wald, Nov., 1876. 



^ Bcobachtungen iiber die Beschaffenheit des Zellkerns, Archiv 

 fiir Mikrosls. Anat., Bd. xiii, 1876, p. 693, and following. 



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