1906] _. OLIVE—NUCLEAR AND CELL DIVISION OF EMPUSA 239 
There can hardly be any doubt, especially after we make compara- 
tive observations on Empusa aphidis, which has a similar type of 
nuclear division, that such stretched-out nuclei as are shown in these 
figures get their peculiar form from the currents of protoplasm flow- 
ing in these long coenocytic hyphae. Resting nuclei, as is well known, 
are plastic to a remarkable degree, and thus, in long cells, may fre- 
quently become much elongated; so it seems more than probable 
that these dividing nuclei may likewise become stretched out in the 
_ same way. 
Figs. 66, 67 represent poorly stained nuclei of Empusa aphidis in 
which division is taking place in a manner evidently similar in every 
respect to that described above as the second type. Here too we have 
vegetative hyphae in which septa are few and far apart; hence the 
general protoplasmic movements must disturb considerably the divid- 
ing nuclei. Practically all of the nuclei of this species conform to the 
type shown in figs. 66, 67, for I have but once found a doubtfully ellip- 
tical nucleus. The fact that the second type of division alone occurs 
in the long tubular filaments of Empusa aphidis points therefore to 
the conclusion that the stretching out of the dividing nuclei in these 
instances is brought about by cyclosis. In this second type of divi- 
sion here described, we can readily imagine that the protoplasmic 
currents also assist materially in the constriction and final separation 
also of the halves of the dividing nucleus. We may thus conceive, in 
the one case, of the protoplasm as undergoing such limited movements 
on account of its confinement in a short cell, so that the dividing 
nucleus is but little disturbed, and consequently, by the accumulation 
of karyolymph, it assumes a short oval or rounded shape; whereas in 
instances where the cells are long and the protoplasmic currents there- 
fore stronger, the dividing nuclei become drawn out and elongated, 
and constriction becomes very early evident. 
In jigs. 64, 65, we note an interesting phenomenon. Here occurs 
an infolding at the poles, giving an appearance as if some stress had 
indented the nuclear membrane at this point. I have not observed 
this phenomenon in the oval nuclei of the first type, but it apparently 
occurs not infrequently in nuclei of the second type. It is possible 
of course, that the infolding may be an artifact, caused in some man- 
ner by the reagents. Such cases furnish indisputable proof, at any 
