KARYOKINESIS AND ITS RELATION TO FERTILIZATION. 207 
still to be done in the investigation of matters of fact, and as 
we know next to nothing as to the origin of the nuclear spindle 
and polar rays (polar streaming), about their fate, about the 
nuclear membrane, about the behaviour of nucleoplasm, about 
the chemical and physical constitution of the chromatic and 
achromatic substances, and as it is still an unsettled controversy 
between the foremost authorities on the subject, Flemming 
and Strasburger, as to how far the cell-body shares in karyo- 
kinesis—since even the equatorial longitudinal splitting as a 
typical phenomenon is disputed, we are not yet in a position to 
formulate any well-founded theory about karyokinesis. Yet I 
must oppose those who, like Brass (38, 39), Fraisse (69), and 
Fol (68), would deny to the chromatic nuclear figure any 
essential significance. Brass maintains that the chromatic 
substance is simply nutritive material for the rest of the 
nucleus and cell, which is stored up in the nuclear network in 
order to be utilised for the life and maturation of the cell and 
nucleus. To the clear plasma of the nucleus (Kernsaft) he 
ascribes the most important active réle in all the phenomena 
of life of the cell and nucleus, especially during division. The 
chromatic substances he regards as passive masses; they are 
attracted by the two nuclear poles, and follow the movements 
of the nucleoplasm. Certainly it would be an exaggera- 
tion to regard the chromatic figure as the chief thing in 
nuclear division, and to place the motive power in the substance 
composing it. At the same time we must guard against the 
error of denying to them their proper significance in nuclear 
division. The facts brought forward, on which Brass depends, 
do not in the least warrant his assumption. His statement 
‘that in starved cells the chromatic nuclear figure is absent, or 
if present is imperfect, does not appear to be universally true, 
inasmuch as Rabl (165) found in a salamander, which had re- 
mained for five months without nourishment, abundant chro- 
matic substance in the division figure. If it is true, as Rabl says, 
that a ground-plan of the chromatin-containing thread, with 
polar and antipolar areas, persists even in a perfectly resting 
nucleus, it is difficult to regard it as quite meaningless, and to 
VOL, XXX, PART 2.—NEW SER, ) 
