NUCLEAR DIVISION OF NOCTILUCA. 257 



a fact which accords well with the phenomena described ten 

 years ago by Th. Boveri ('88) in his epoch-making work on 

 cell division under the expression of " Dualismus der Kernthei- 

 lungsphenomene." The same phenomenon was again observed 

 by BovERi and formulated by him last year in his highly in- 

 teresting paper on the "Physiologie der Kern- und Zelltheilung" 

 as follows: — "Daraus ergiebt sich erstens, dass die in bestimmten 

 Intervallen eintretende Zweitheilung des Centrosoma, die Ent- 

 fernung der Tochtercentrosomen von einander, die Ausbildung 

 und Rückbildung der strahligen Protoplasma-Anordnung vom 

 Kern vollständig unabhänging sind " ('97, p. 2). This conclu- 

 sion arrived at by Boveei from experimental studies on sea- 

 urchin eggs, was confirmed by E. H. Ziegler ('98, b) who also 

 worked on eggs of the same animal. It may not be out of place 

 here to remark that in both unicellular and multicellular orçran- 

 isms the formation of the spindle in cells with or without nu- 

 cleus is not only interesting in itself, but also as showing that 

 there exists no correlative action between the nucleus 

 and the kinetic centres lying in the cytoplasm, and 

 that the mosaic hypothesis can as Avell be applied here 

 as in the developmental stages of multicellular or- 

 ganisms. 



Tokyo Imperial Universitj'-, 



College of Agriculture, 



End of November. 



