KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 199 
all be derived from one fundamental form, or one from another ? 
The regular, simple amitotic division would in the latter case 
be the first, and regular mitosis the final member of the series. 
I must confess, as previously remarked, that even after 
Tangl’s and Strasburger’s objections, I cannot rid myself of 
the idea that nuclear division is a single process, with Remak’s 
simple amitotic division as the fundamental form. The affir- 
mative preparations of Pfitzner-and Sattler are on my side, and 
even if an intermixture of nucleoplasm (Kernsaft) and cell- 
protoplasm takes place, the existence of the nucleus does not 
thereby become restricted to its chromatic constituents alone. 
On the other hand, we find, immediately after the reconstruction 
of the daughter-nuclei, the achromatic uniting with the chro- 
matic constituents. Add to this the varied subforms, e.g. in 
Spirogyra, where the nuclear membrane disappears only after 
the formation of the spindle figure. Flemming, too, contributes 
similar observations, which he directs against the doctrine of 
the derivation of the spindle figure from the cell-proto- 
plasm, as has been mentioned above. The recognised cases in 
various Protozoa of mitosis with retention of the nuclear mem- 
brane belong here. Arnold’s observations, too, on mitotic 
segmentation and fragmentation must be here mentioned. 
Arnold himself (in a short publication) recognises subforms in 
mitotic fragmentation. I would interpret the facts in such a 
way that we have to regard as the fundamental form the simple 
amitotic division which is now proved for many cases; it 
always takes place where the nucleus either is poor in chro- 
matin, or when it does not matter about strict bipartition of 
the chromatic material. Should the latter be required, then we 
shall find mitosis, since it is the most direct, most certain, 
and most simple manner in which an exact bipartition of 
chromatic substance is brought about. This may well be 
considered as the aim of karyokinesis.' 
As to this aim, see further below in the theoretical considera- 
tion of mitosis. 
1 See the repeatedly quoted memoirs of Carnoy, ‘La cellule,’ I, “ Arthro- 
poda,” p. 395. ‘ Rapports entre les deux modes de division,’ 
