Overton—On the Boot Tips of Podophyllum Peltatum . 289 
I have described as paired at the telophase, may again reform in 
pairs during the prophases, but I regard this as rather strong 
evidence. I can find no evidence from my studies to support the 
hypothesis of Fraser and Snell (’ll) and of Digby (’19) that 
each prophasic chromosome is formed of two units derived from 
a single chromosome and that the units of each pair are separated 
during the subsequent division. 
Sharp (’13, 20b) holds that the first indication of prophasic 
changes is the breaking down of the lateral anastomoses between 
the heavier portions of the reticulum, so that each chromosome 
stands out as an irregular reticulate, alveolar band, and points 
out that such bands may probably be visible all through the period 
of rest. With these statements my results accord, except, as 
above stated, that I do not find evidence for lateral anastomoses 
in all cases and that even during the period of comparative rest 
their absence may be evident (fig. 11). The succeeding events 
of chromosome condensation as found in Podophyllum harmonize 
very well with those described by Sharp (’13) for Yicia. I find 
exactly the stages represented by Sharp’s figures 3 to 17, except 
that, as stated above, I am of the opinion that there exist both 
chromatin and linin, while Sharp states that Vicia furnishes no 
good evidence for the existence of more than one substance in the 
chromatic structures. Mottier (’07) in his studies on the reduc¬ 
tion division in Podophyllum speaks of the nuclear reticulum as 
being made up of both linin and chromatin. 
In examining figures 11 and 12, the reticulum of the bands 
can be seen to be made up of irregular granules imbedded in the 
linin substratum. Bridges of linin appear to connect the granules 
of a band together very regularly. On closer examination and 
study, however, the structure will be seen to be very similar to 
that shown in figures 9 and 10, only more condensed. As the 
prophases proceed, the linin connections between any two or more 
granules appear coarser and more chromatic in content. This 
condition is especially observable in the two bands favorably placed 
for study near the periphery on the right of the nucleus shown 
in figure 13. These bands appear to be made up of irregular 
granular chromatic platelets connected by linin strands. The 
alveoli appear fewer and may open freely into neighboring al¬ 
veoli or into the nuclear sap. Out of these granular platelets by 
some method, which I have not been able to make out to my en¬ 
tire satisfaction, and out of the linin connections a long, thin, 
19—S. A. L. 
