362 BULLETIN OF THE 



The points in the metamorphosis of the nucleus to which Flemming 

 has here called attention for the first time are: — (1.) tlie first stage, 

 which is not granular, but presents a connected system of curled, very- 

 fine filaments ; (2.) the delicate glomerule stage which immediately fol- 

 lows; (3.) the loosening in the coils; (4.) the stage with peripheral and 

 central loops; (5.) the rupture of the loops to form a star; (6.) the 

 fission of the filaments ; (7.) a bipolar arrangement of the figure during 

 a series of rhythmical contractions and expansions ; (8.) the fact that 

 the daughter nuclei do not at once form a homogeneous mass, but pass 

 in reverse order through the stages which the parent nucleus undergoes 

 during the metamorphosis. 



The objections which Auerbach ('76) has raised against identifying 

 the spindle- or nuclear-figure with the mother nucleus are answered by 

 Flemming point by point : — (1.) the nuclear figure is not always larger 

 than the quiescent nucleus, and in cases where it is larger the old nu- 

 cleus has already before division so increased in size that the masses of 

 both nearly agree ; (2.) the sharp nuclear membrane, it is true, is lost, 

 but the nuclear figure still remains sharply limited from the cell plasm ; 

 (3.) there is no stage found in Salamandra where the old nucleus has 

 actually or apparently disappeared, but the nuclear figure is morphologi- 

 cally derived from it ; (4.) the new nuclei do arise from a division of the 

 old nucleus. It remains, however, to ask, says the author, whether in 

 the formation of the nuclear figure anything is taken from the protoplasm, 

 whether anything of the substance of the nucleus goes at this time to the 

 protoplasm, and, finally, if any like change takes place during the growth 

 of the new nuclei. All three suppositions are possible. It is certain 

 that the clear substance between the curled filaments does not directly 

 go to the new nuclei. One cannot, then, hold to a complete identity of the 

 nuclear figure with the nucleus. In red blood-corpuscles a large part of 

 the cell substance, in fact, almost the whole of it, is incorporated in the 

 division figure. If this is not the case in other cells, it can hardly be 

 denied that a small part of the substance of the nuclear figure is an- 

 nexed from the protoplasm. An exchange between nuclear substance and 

 plasma as a general phenomenon is, if not proved, at least to be assumed 

 as possible. Fol, Auerbach, and the author himself, says Flemming, 

 have rightly maintained that a cell division in Remak's sense does not 

 cover the facts, but they have as certainly fallen into error in maintain- 

 ing that no formal element of the nucleus remains.* 



* "Dass ein solcher Kern bei der Theilung nicht bestehen bleibt (i. e. as mem- 

 brane, contents, and nucleoli) und sicli nuM direct entzweischniirt, dass also die alte, 



