KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 168 
same author, is now contrasted with another mode of divi- 
sion, the ‘mitotic division” (‘ karyomitosis,”’ “ mitosis,” or 
‘indirect division”? of Fleming; ‘‘ karyokinesis ” or “ karyo- 
kinetic division” of Schleicher), the appearance of which 
differs in many respects from direct division. The striking 
and characteristic features of this mode of division lie in 
the fact that the nucleoli as well as the nuclear membrane 
disappear, or rather seem to disappear. Moreover, as already 
remarked, the place of the nucleus is taken by a very charac- 
teristic figure of threads, which changes in form and arrange- 
ment in a perfectly well-ascertained way, then withdraws 
towards the two sides, and forms the basis for two daughter 
nuclei. At the point where these are formed certain peculiar 
radiating appearances in the protoplasm are seen pretty early — 
stars, “asters,” or “sunfigures.” Cell-division then follows, 
in the usual way, after nuclear division. 
On account of the change in position and arrangement of 
the nuclear threads, Schleicher has, as stated, given the name 
*‘ karyokinesis ” or “ karyokinetic division” to the whole pro- 
cess, whilst Flemming’s terms, “ mitosis ” and “ karyomitosis,” 
refer to the appearance of the above-mentioned thread figure.! 
The name “‘ indirect division” is well chosen only in con- 
trast to “direct division ;” otherwise it seems, as Flemming 
admits, but little appropriate. 
I will now represent in figures, copied chiefly from Rabl 
(165), some of the processes of karyomitosis, but I must 
briefly describe the essential structure of a nucleus not engaged 
in division, a so-called “ resting nucleus.” 
In most of such nuclei (fig. 1) there can be distinguished the 
network (“ Kerngerust”’), the nucleoli (‘ Kernkorperchen ”’), 
the nuclear sap (“ Kernsaft” of R. Hertwig or ‘‘ Zwischen- 
substanz ” of Flemming), and the nuclear membrane. Without 
going into the extensive literature, rich in controversy, on 
the subject, it is necessary to discuss further some of the 
details. 
The nuclear net work, in the ordinary condition of a nucleus 
1 Kadpvoy, nut, nucleus; xevnoe, motion ; proc, thread, 
