Overton—On the Root Tips of Podophyllum Peltatum. 305 
form a small nucleus. That chromosomes may regularly be un¬ 
equally distributed and form small nuclei is found by Juel (’97) 
and Schurhoff (T3) in the pollen mother cells of Hemerocallis 
fvlvu, and I have observed a like condition in the pollen mother 
cells of Paeonia mutan. 
Typical karyomere formation in somatic cells of plants, as 
Nemec (’10) pointed out, had been observed up to that time only 
by Gregoire (’03), during the second division of the pollen mother 
cells of Trillium cernuum. In this plant several nuclei arise each 
of which is either mono- or polychromosomatic, but Gregoire holds 
that normally sooner or later the single nucleus results from a 
confluence of the chromosome vesicles. Nemec (’10) describes 
similar chromosome vesicles in Chara fragilis, in which the chromo¬ 
somes do not closely mass after metakinesis, as is usually the case. 
Nemec states that in small cells a single nucleus is constructed from 
all the chromosomes, but in large cells several individual nuclei 
are formed which soon after reconstruction fuse to form a single 
nucleus. Sehiirhoff (T3) also reports that the karyomeres of 
Hemerocallis fuse to form one nucleus. Lundegard (’12a) would 
regard the formation of karyomeres as a special and not a usual 
phenomenon in nuclear division, connected with the fact that the 
chromosomes are in some cases not closely associated, which fact 
Lundegard holds may explain the tendency of the young daugh¬ 
ter nuclei of Allium to show alveolated lobes, formed from the 
separated ends of the daughter chromosomes which have become 
surrounded by a membrane. 
As described above, I have observed a constant though not a 
universal lobing of the daughter nuclei similar to that described 
and figured for Allium by Gregoire (’06) and by Lundegard 
(’12c). I am of the opinion that these karyomeres are formed, 
as Lundegard suggests, by the rather widely separated chromo¬ 
somes becoming alveolated. Instead of the chromosomes becom¬ 
ing surrounded by a membrane as held by Lawson (’ll, ’12), I 
believe that the membrane about each chromosome is always pres¬ 
ent and that the karyomeres never fuse in the sense that they an¬ 
astomose, as held by Gregoire (’03), Nemec (TO), and Lunde¬ 
gard (T2c) even at their polar ends, but that the only connec¬ 
tion between the chromosomes is by the inosculation of neighbor¬ 
ing vacuoles of two adjacent chromosomes. This view finds sup¬ 
port in the fact that in Podophyllum the chromosome bands are 
20—-S. A. L. 
