﻿i 9 i6] MERRIM AN— NUCLEAR DIVISION 317 



overlying a less deeply stained material. Other figures show minor 

 variations from those previously mentioned. In comparison, all 

 that these stages appear to have in common is the increasing 

 tendency of the material, chromatic and non-chromatic, to be 

 peripherally arranged on a sphere. 



Metaphase living 



As the enveloping protoplasm gradually becomes more tenuous, 

 adding substance to the retreating folds, the ellipsoid mass changes 

 and becomes cylindrical. This appears to be due to the accumula- 

 tion of denser portions on the surface and the gradual penetration ' 

 of more liquid material to the interior. This may be forced out at 

 the poles as the denser materials assume the form of a disk (figs. 5, 

 15, 16). The cylinder as it elongates loses progressively its turbid 

 appearance. As the turbidity diminishes, the equatorial part 

 retains the gray tint, forming gradually a dark band (fig. 17), 

 while light bands by degrees evolve, encompassing the cylinder one 

 on either side of the equator (figs. 16, 18). These bands as they 

 assume concrete form acquire a translucent appearance. They 

 condense into two disks connected by fragments of cords of a 

 similar translucent appearance. It is to be seen, therefore, that 

 instead of a sharp splitting and consequent clear-cut separation of 

 equatorial masses of the cylinder occurring, no actual narrow rift 

 was perceptible, although many nuclei at this stage were closely 

 scrutinized for the expected splitting. There is no evidence in 

 living material of these two disks having arisen from the splitting 

 of discrete chromatic bodies. It is as if a gradual accumulation 

 and rearrangement of materials had taken place, until finally the 

 dense materials, appearing as jelly-like disks, are moving to the 

 poles of the spindles, while vestiges of cords drag behind (figs. 19, 20). 



Metaphase fixed 



Figs. 34 and 35 represent transitional stages where the nuclear 

 membrane has dissolved. Here the mass of stained material is 

 beginning to lose its spherical shape; and the suspensors change, 

 some in the long axis of the cell increasing and appearing as lines 

 of granules directed, not as before, away from the margin of the 



