MUSEUM OF COMPAEATIVE ZOOLOGY. 303 



contour of the former becomes indistinct, and its form irregular, owing, 

 possibly, to its amoeboid movements. The nucleoli disappear. The 

 substance of the nucleus is soon divided into two parts : the one, which 

 is clear and transparent, and which is not colored in either carmine or 

 hsematoxylin, is the sue nucUaire ; the other, which is likewise homo- 

 geneous, but which becomes deeply stained, and forms an irregular 

 lump (grumeau) in- the middle of the nucleus, is the essence nucleaire. 

 The nuclear sap accumulates at the two poles of the elongated nucleus ; 

 the " essence," at the middle of the nucleus, to form the equatorial 

 plate. The faces of the latter are bunched, and consequently irregular. 

 It seems formed of very refrhigent globules of an ovoid, or of a rod-like 

 form. Whatever the method of treatment, the nucleus was never found 

 at this time to be striated, either longitudinally or transversely. The 

 body of the cell undergoes concomitant changes of form ; it also be- 

 comes more granular, and slightly stained by coloring fluids, these lat- 

 ter peculiarities serving to distinguish at once the cells in process of 

 division. 



The nucleus becomes spindle-shaped, then flattened (ruban^). At its 

 poles there accumulates, in the body of the cell, a little clear, finely 

 granular substance, which the author hesitated to identify with his 

 pronucleus engendre, though he would at present probably not entertain 

 any doubt as to the correctness of this identification. This polar mass 

 becomes the centre of a stellate figure developed in the protoplasm of 

 the cell, and indicates very manifestly the attraction exercised by the 

 poles of the old nucleus upon the protoplasmic substance of the cell. 

 These stellate figures, already seen by numerous observers in segmenta- 

 tion spheres, have not been previously pointed out, so far as the author 

 knows, in ordinary cells. 



The equatorial granular plate divides into two parallel disques nu- 

 cleaires, which separate as though mutually repulsive. These two plates 

 are connected by filaments (Kernfaden of Strasburger) , which appear 

 to be thrown out by some of the granules which constitute the disks. 

 After the disks have separated from each other, these filaments are 

 drawn in, and blend with their substance. Meanwhile, the nucleus 

 takes the form of a band with parallel edges, and the nuclear sap (very 

 faintly rose-colored in picrocarmine) , which had at first been repelled 

 to the poles of the nucleus, is accumulated between the two disks. The 

 latter finally reach the extremities of the nuclear band, and come into 

 immediate contact with the small, clear mass at the centre of the stel- 

 late figures. The clear band, which is the remnant of the old nucleus. 



