KARYOKINESIS AND ITS RELATION TO FERTILIZATION, 209 
poles of the nucleus, in order to return to rest again with the 
typical fundamental figure.' 
At present we cannot give an explanation of the variety of 
form of karyokinetic figures: at least it is purely hypothetical, 
when Carnoy (loc. cit., p. 402) suggests as the aim of karyo- 
kinesis, that it leads to the restoration of the dicentricity of 
the cell, that it renders possible a complete regeneration of nu- 
clear constituents, and imports into the cell-protoplasm new 
plastin elements. It is still difficult to understand polar star- 
formation and the spindle figure: the attention of future 
workers will have to be concentrated particularly on these. 
That the nuclear membrane disappears seems quite intel- 
ligible, when we consider that such an envelope would be a 
decided hindrance to a division of the totality of the nucleus. 
This, too, is a point which requires further explanation, espe- 
cially as we do not yet even know correctly what happens to 
the nuclear membrane. 
It is clear from what has just been said that the theoretical 
appreciation of karyokinetic phenomena is still in an unsatis- 
factory position, and that no particular significance can be 
assigned to its details. On the other hand, they seem to have 
significance in relation to some other facts, as has been already 
pointed out,—I mean in all questions dealing with the 
phenomena of proliferating new formations (Neubil- 
dungen) and regeneration in plants and animals. 
Formerly, if we wished to ascertain what cellular element was 
concerned in such a process, from what particular point and 
what special cells, for example, the normal growth or rege- 
1 For plant-cells, Strasburger in his latest memoir (191) lays it down as a 
general occurrence that the chromatic loops consist of thick tub-shaped 
“chromatin-scheiben,” regularly alternating with thin ‘‘ linin-scheiben.” 
During the process of karyokinesis, as in a passage from a resting to a 
kinetic form, the chromatin granules are seen to gradually approach and fuse 
to form the “‘ scheiben;’’ thereby the mass of chromatin is increased, whilst 
that of the connecting linin decreases. The reverse takes place in the forma- 
tion of daughter-nuclei. Strasburger is of opinion that this regular storage of 
chromatin, preceding the longitudinal splitting of the threads, is a contrivance 
for the closest possible halving of it in division. 
