Overton—On the Root Tips of Podophyllum Peltatum. 291 
denee that they arise or that they are formed in lateral pairs 
closely associated. In every case I am convinced that they are 
formed from a single chromatic band as above described, and as 
Sharp (’13) maintains for Vicia. In my opinion the zigzag stage 
of the prophase in Podophyllum always precedes the formation 
of the thicker coiled spirem, which is apparently the conclusion 
of Sharp (’13) regarding Yicia. 
Most authors place the spirally coiled spirem in the same place 
in the series as I have done for Podophyllum. In examining 
Strasburger’s (’82) early figures of corresponding prophase stages 
of the endosperm nuclei of Fritillaria imperalis (his fig. 72, PI. 
II) , I find that he evidently saw the same sort of spirem, which he 
places immediately after the resting stage of the nucleus. He 
also showed a similar stage for Salamandra (see his fig. 182, PI. 
III) , and Flemming (’82) also figured and described a somewhat 
similar spirem for Salamandra (his fig. 31, PI. Ilia). He said: 
“Die Anordnung des Fadenknauls zeigt in den Anfangsformen noch 
vielfach scharfere winklige Knickungen, wie solche an den Balkchen des 
ruhenden Kernnetzwerks die Regel sind. Je weiter aber der Process 
bedeiht, desto mebr gleichen sich diese Knickungen zu welligen Biegungen 
aus, die schliesslich durchweg vorkommen.” 
The thin homogenous threads of the zigzag or coiled spirem split 
longitudinally, as shown in figures 17 and 18. As pointed out 
by Sharp (’13) for Yicia, not all portions of the thread split at 
the same time, and all stages intermediate between vacuolation 
and a complete split may be seen. 
Strasburger (’05, ’075, ’ll) holds that the splitting of the 
spirem is brought about by the division of chromatic units or 
chromomeres, a view supported by Allen (’05) and others. Mul¬ 
ler (’12) holds that the achromatic material between the chromo¬ 
meres first splits, and that the splitting of the chromosomes then 
follows. Sharp (’13) finds no evidence for the support of either 
view from his studies on Yicia. Sakamura (’14) finds no evidence 
of chromomeres in Vicia cracca. 
In my former studies (Overton (’05, ’09a) on reduction divi¬ 
sions in certain dicotyledonous plants, I was unable to find the 
regular arrangement of chromomeres above referred to. This 
was especially the case in the heterotypic division of Podophyllum. 
Mottier (’07), however, figures chromomeres in the heterotypic 
divisions of this plant. In the present studies on the somatic 
