KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 181 
or from the cell-substance, with two poles; the arrangement 
of the chromatic elements, so far as their number, size, 
and form allow, in the equatorial plane of the achromatic 
figure ; the division of the chromatic elements into two halves, 
of which one half goes to either pole; the transformation of 
the daughter elements into the network of two new nuclei.” 
We have now to speak in greater detail of certain points 
which have hitherto been only cursorily touched upon, and to 
add others which have not yet been mentioned. In the first 
place I must beg leave to propose a separate technical name 
“‘chromosome ” for those things which have been called by 
Boveri ‘‘chromatic elements,” in which there occurs one 
of the most important acts in karyokinesis, viz. the longi- 
tudinal splitting. The name “ primary loops” does not do, 
since these things have not always the form of aloop. ‘‘ Chro- 
matic elements” is too long. On the other hand, they are so 
important that a special and shorter name appears useful. 
Platner (160) employed the term “ karyosome,” but since this 
suggests the nucleoli another name ought to be used. If the 
one I propose is practically applicable it will become familiar, 
otherwise it will soon sink into oblivion. 
In the second place, with regard to the spindle figure and 
the radiating figure in the protoplasm, these are shown 
in figs. 5—11. The spindle figure was first figured and briefly 
described by Alexander Kowalevsky, then at Kiew, in his 
renowned work (114), ‘ Embryologische Studien um Wiirmern 
und Arthropoden.? The polar rays in the cell-protoplasm 
which emanate from each pole of the spindle figure were first 
shown to us by Herman Fol, of Geneva (64), and A. Schneider 
(181). Whereas Fol and Schneider give good figures and 
descriptions of the polar rays, that of Kowalevsky of the. 
spindle figure is incomplete, and he interprets it as being due 
to a division of the nucleoli. Carnoy (47) has recently come 
to the conclusion that the nucleoli take a share in the forma- 
tion of the spindle-threads. Biitschli (41, 42) was the first to 
give us minute details. In spite of the numerous researches 
which have been directed towards this point by Flemming, 
