162 W. WALDEYER. 
directions from the two ends, as if pulling these apart. The 
division of the cell-body lasted eight and a half minutes, so 
that the complete process occupied ten minutes. 
I have studied the process in a similar way in an Infusorian 
from the Frog’s rectum ; it took place somewhat more rapidly, 
viz. in seven or eight minutes. Ranvier gives an hour and a 
half, at the usual temperature of the room, as about the time 
occupied by the process of division in leucocytes of Axolotl; 
a remarkable change of form was observed in the nucleus, 
which, however, was regarded by Ranvier as passive—con- 
ditional only on the amceboid movement of the protoplasm. 
J. Arnold (4) observed in amoeboid cells of the lymph- 
sac of Frogs an undoubtedly constricted nucleus, divide 
completely within five minutes; the division of the cell 
occupied in this case half an hour, in other cases longer. 
Change of form in the nucleus and protoplasm was likewise 
established. 
Of the researches of Stricker and Klein, I will here merely 
mention that they were the first to establish the process of the 
division of the cell-substance, but they give no explanation of 
the relation of the nucleus to the act of division. 
But mention must here be made of a circumstance which 
was noted by Stricker, and later also by Flemming (58), 
Frommann (73), and J. Arnold (4). It is the disappearance 
of the nucleus for a time during the simple, not karyokinetic, 
division. No satisfactory explanation of this remarkable 
occurrence is at present forthcoming. 
I have here intentionally given the first place to the simple 
process of nuclear and cell division, as it was inferred by 
Remak, and as it was directly studied by the other authors 
named, chiefly in order to be able to emphasise the 
character of the karyokinetic division about to be described, 
and because, as we shall see later, the old scheme of 
nuclear division remains essentially true, even in the karyo- 
kinetic form. 
This scheme of Remak’s, which we will, with Flemming, call 
“direct nuclear division,’ or ‘ amitotic division” of the 
