Overton—On the Boot Tips of Podophyllum Peltatum. 285 
the daughter chromosomes unite end to end to form a daughter 
spirem. Such a spirem has not been found by Gregoire or by any 
of his co-workers, and has not been observed by Lagerberg (’09) 
in Adoxa. In all the plants which possess prochromosomes, as 
first described by Rosenberg (04) and since by several other in¬ 
vestigators, the absence of a continuous chromatic spirem has 
been noted. In agreement with most recent work on other forms, 
and as has been emphasized by Sharp (’13), I have been unable 
to find a continuous spirem formed from the daughter chromo¬ 
somes of Podophyllum. Although during the reconstruction 
stages of Podophyllum I have sometimes observed appearances of 
a dispirem (figure 23), I have never been convinced of its uni¬ 
versal existence in this plant, and am inclined to the view held by 
Gregoire that it does not obtain either in this plant or in Allium. 
If there is anything comparable to a dispirem, it certainly is not 
completely and continuously chromatic in character. In figures 
5, 6, and 7 there seems to be no tendency for the chromosomes to 
unite endwise into a spirem. Each chromosome is undergoing 
the internal modifications above described. In figure 8, in the 
nucleus of the lower cell, each chromosome is still free and not 
united with any of its associates. 
In the lower cell of figure 8 each chromosome may be seen to be 
surrounded by a definite membrane much as has been described 
for karyomeres or chromosome vacuoles in certain animal cells. 
The cytoplasm in many places may also be seen to extend in be¬ 
tween these alveolated structures. By a constant progressive al- 
veolation and reticulation of these chromosomes they come to lie 
closer and closer together, so that the cytoplasm is shoved aside 
and the chromosomes touch each other in places. This is evident 
in the upper nucleus in figure 8. If the chromosomes first touch 
at the polar ends, peculiar lobe-shaped structures arise giving a 
lobed appearance to the nuclei, as shown in figure 8 and also in 
figure 12. Gregoire (’06) in his figure 3 has represented a simi¬ 
larly lobed nucleus in Allium, and I have also often observed like 
conditions in the same plant. Gregoire, however, shows these lobes 
as distinctly anastomosed. Although the lobes in the upper nu¬ 
cleus in figure 8 appear in contact at the polar ends, I do not 
believe that they are anastomosed or that they unite in any way 
except by the inosculation of the vacuoles. This view is further 
supported by a study of such nuclei as are shown in figures 11 
and 12. These are resting nuclei in the interphase stage, in which 
