1906} OLIVE—NUCLEAR AND CELL DIVISION OF EMPUSA 241 
The lack of accumulation of nuclear sap in the latter type of nuclear 
division constitutes the only difference between this type and the one 
described above. © 
The accumulation of sap in the nucleus in the first instance is prob- 
ably due to the lack of disturbance of the process by the restricted 
protoplasmic currents in the short cells. The lack of accumulation 
of sap in the second instance is probably due to the disturbing 
influences of the stronger protoplasmic movements which undoubtedly 
take place in the long tubular filaments. In the first type the 
chromatic substance in the newly formed daughter-nuclei comes to lie 
in a mass at one side of the nuclear cavity, thus resembling somewhat 
a synaptic condition. In the other, the nuclear materials of the young 
daughter-nucleus, massed about the centrosome, are closely enveloped 
by the surrounding cytoplasm, and not until later in the reconstruc- 
tive processes which follow, does the nuclear sap appear. 
Towards the close of division, the center in each nucleus comes to 
lie close to, if not actually on, that portion of the nuclear membrane 
nearest the pole. Its attachment and anchorage to the nuclear mem- 
brane is proven by the frequent indentation of the membrane at this 
point. In the young nucleus the center remains conspicuous for some 
time, but finally, with the resumption of a resting condition, it becomes 
entirely lost to view. In the resting nucleus, the nuclear materials 
appear to be distributed more or less evenly on a much convoluted, 
seemingly homogeneous, filamentous thread which resembles a spi- 
rem. 
We have now to emphasize, before entering upon a discussion of . 
the general bearing of these facts, certain peculiarities at once notice- 
able in this primitive mode of nuclear division. In the type first de- 
scribed, the nuclear membrane plainly persists throughout the whole 
process of division; also in certain nuclei of the elongated type, it 
undoubtedly persists (figs. 65-67), although it is here not so conspicu- 
ous. I am inclined further to regard a membrane as present around 
the chromatic fibers in jigs. 62-64, notwithstanding the fact that in the 
preparations it cannot be seen. The iron haematoxylin stain is prob- 
ably accountable for the failure to bring out the membrane clearly in 
this instance. Hence we may record at this point that in the case of 
Empusa, the nuclear membrane is at least usually persistent through- 
