RESEARCHES ON KARYOKINESIS AND CELL DIVISION. 49 



sents itself in connection with this subject is, whether 

 there is any free formation of nuclei independent of pre- 

 existing nuclei. Such a free formation would seem to 

 take place, according to the researches of Van Beneden, 

 in the endodermal cell of Dicyemidse. F. Schmitz (loc. 

 cit.) was unable to find nuclei in the cells of Phycochro- 

 macese, so that these at present form an exception to the 

 general rule, that when a cell divides each portion includes 

 a portion of the original nucleus. But it is not long since 

 the independent origin of nuclei in -the ovum of animals 

 and the embryo-sac of Phanerogamia was generally accepted ; 

 and it is probable that future researches will enable the 

 questions still unsettled, with reference to the multiplica- 

 tion of cells in cases which now seem exceptional, to be 

 more definitely decided. 



VOL. XXII. NEW SER. 



